speech human definition

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Losing her speech made her feel isolated from humanity.

Synonyms: communication , conversation , parley , parlance

He expresses himself better in speech than in writing.

We waited for some speech that would indicate her true feelings.

Synonyms: talk , mention , comment , asseveration , assertion , observation

a fiery speech.

Synonyms: discourse , talk

• any single utterance of an actor in the course of a play, motion picture, etc.

Synonyms: patois , tongue

Your slovenly speech is holding back your career.

• a field of study devoted to the theory and practice of oral communication.
• Archaic. rumor .

to have speech with somebody

speech therapy

• that which is spoken; utterance
• a talk or address delivered to an audience
• a person's characteristic manner of speaking
• a national or regional language or dialect
• linguistics another word for parole

Discover More

Other words from.

• self-speech noun

Word History and Origins

Origin of speech 1

Synonym Study

Example sentences.

Kids are interacting with Alexas that can record their voice data and influence their speech and social development.

The attorney general delivered a controversial speech Wednesday.

For example, my company, Teknicks, is working with an online K-12 speech and occupational therapy provider.

Instead, it would give tech companies a powerful incentive to limit Brazilians’ freedom of speech at a time of political unrest.

However, the president did give a speech in Suresnes, France, the next day during a ceremony hosted by the American Battle Monuments Commission.

Those are troubling numbers, for unfettered speech is not incidental to a flourishing society.

There is no such thing as speech so hateful or offensive it somehow “justifies” or “legitimizes” the use of violence.

We need to recover and grow the idea that the proper answer to bad speech is more and better speech.

Tend to your own garden, to quote the great sage of free speech, Voltaire, and invite people to follow your example.

The simple, awful truth is that free speech has never been particularly popular in America.

Alessandro turned a grateful look on Ramona as he translated this speech, so in unison with Indian modes of thought and feeling.

And so this is why the clever performer cannot reproduce the effect of a speech of Demosthenes or Daniel Webster.

He said no more in words, but his little blue eyes had an eloquence that left nothing to mere speech.

After pondering over Mr. Blackbird's speech for a few moments he raised his head.

Albinia, I have refrained from speech as long as possible; but this is really too much!

Related Words

More about speech, what is speech .

Speech is the ability to express thoughts and emotions through vocal sounds and gestures. The act of doing this is also known as speech .

Speech is something only humans are capable of doing and this ability has contributed greatly to humanity’s ability to develop civilization. Speech allows humans to communicate much more complex information than animals are able to.

Almost all animals make sounds or noises with the intent to communicate with each other, such as mating calls and yelps of danger. However, animals aren’t actually talking to each other. That is, they aren’t forming sentences or sharing complicated information. Instead, they are making simple noises that trigger another animal’s natural instincts.

While speech does involve making noises, there is a lot more going on than simple grunts and growls. First, humans’ vocal machinery, such as our lungs, throat, vocal chords, and tongue, allows for a wide range of intricate sounds. Second, the human brain is incredibly complex, allowing humans to process vocal sounds and understand combinations of them as words and oral communication. The human brain is essential for speech . While chimpanzees and other apes have vocal organs similar to humans’, their brains are much less advanced and they are unable to learn speech .

Why is speech important?

The first records of the word speech come from before the year 900. It ultimately comes from the Old English word sprecan , meaning “to speak.” Scientists debate on the exact date that humanity first learned to speak, with estimates ranging from 50,000 to 2 million years ago.

Related to the concept of speech is the idea of language . A language is the collection of symbols, sounds, gestures, and anything else that a group of people use to communicate with each other, such as English, Swahili, and American Sign Language . Speech is actually using those things to orally communicate with someone else.

Did you know … ?

But what about birds that “talk”? Parrots in particular are famous for their ability to say human words and sentences. Birds are incapable of speech . What they are actually doing is learning common sounds that humans make and mimicking them. They don’t actually understand what anything they are repeating actually means.

What are real-life examples of speech ?

Speech is essential to human communication.

Dutch is just enough like German that I can read text on signs and screens, but not enough that I can understand speech. — Clark Smith Cox III (@clarkcox) September 8, 2009

I can make squirrels so excited, I could almost swear they understand human speech! — Neil Oliver (@thecoastguy) July 20, 2020

What other words are related to speech ?

• communication
• information

Quiz yourself!

True or False?

Humans are the only animals capable of speech .

Speech Production

• Reference work entry
• First Online: 01 January 2015
• pp 1493–1498
• Cite this reference work entry

• Laura Docio-Fernandez 3 &
• Carmen García Mateo 4  

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Sound generation; Speech system

Speech production is the process of uttering articulated sounds or words, i.e., how humans generate meaningful speech. It is a complex feedback process in which hearing, perception, and information processing in the nervous system and the brain are also involved.

Speaking is in essence the by-product of a necessary bodily process, the expulsion from the lungs of air charged with carbon dioxide after it has fulfilled its function in respiration. Most of the time, one breathes out silently; but it is possible, by contracting and relaxing the vocal tract, to change the characteristics of the air expelled from the lungs.

Introduction

Speech is one of the most natural forms of communication for human beings. Researchers in speech technology are working on developing systems with the ability to understand speech and speak with a human being.

Human-computer interaction is a discipline concerned with the design, evaluation, and implementation...

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T. Hewett, R. Baecker, S. Card, T. Carey, J. Gasen, M. Mantei, G. Perlman, G. Strong, W. Verplank, Chapter 2: Human-computer interaction, in ACM SIGCHI Curricula for Human-Computer Interaction ed. by B. Hefley (ACM, 2007)

Google Scholar  

G. Fant, Acoustic Theory of Speech Production , 1st edn. (Mouton, The Hague, 1960)

G. Fant, Glottal flow: models and interaction. J. Phon. 14 , 393–399 (1986)

R.D. Kent, S.G. Adams, G.S. Turner, Models of speech production, in Principles of Experimental Phonetics , ed. by N.J. Lass (Mosby, St. Louis, 1996), pp. 2–45

T.L. Burrows, Speech Processing with Linear and Neural Network Models (1996)

J.R. Deller, J.G. Proakis, J.H.L. Hansen, Discrete-Time Processing of Speech Signals , 1st edn. (Macmillan, New York, 1993)

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Department of Signal Theory and Communications, University of Vigo, Vigo, Spain

Laura Docio-Fernandez

Atlantic Research Center for Information and Communication Technologies, University of Vigo, Pontevedra, Spain

Carmen García Mateo

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Center for Biometrics and Security, Research & National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China

Departments of Computer Science and Engineering, Michigan State University, East Lansing, MI, USA

Anil K. Jain

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Docio-Fernandez, L., García Mateo, C. (2015). Speech Production. In: Li, S.Z., Jain, A.K. (eds) Encyclopedia of Biometrics. Springer, Boston, MA. https://doi.org/10.1007/978-1-4899-7488-4_199

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22 The anatomical and physiological basis of human speech production: adaptations and exaptations

Ann MacLarnon is Director of the Centre for Research in Evolutionary Anthropology at Roehampton University. She has worked on a wide variety of areas in primatology and palaeoanthropology, with an emphasis on comparative approaches. Research topics include reproductive life histories and physiology, stress endocrinology and behaviour, and aspects of comparative morphology including the brain and spinal cord. Work on this last area led to the unexpected discovery that humans evolved increased breathing control for speech.

• Published: 18 September 2012
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This article provides details on human speech production involving a range of physical features, which may have evolved as specific adaptations for this purpose. All mammalian vocalizations are produced similarly, involving features that primarily evolved for respiration or ingestion. Sounds are produced using the flow of air inhaled through the nose or mouth, or expelled from the lungs. Unvoiced sounds are produced without the involvement of the vocal folds of the larynx. Mammalian vocalizations require coordination of the articulation of the supralaryngeal vocal tract with the flow of air, in or out. An extensive series of harmonics above a fundamental frequency, F 0 for phonated sounds is produced by resonance. These series are filtered by the shape and size of the vocal tract, resulting in the retention of some parts of the series, and diminution or deletion of others, in the emitted vocalization. Human sound sequences are also much more rapid than those of non-human primates, except for very simple sequences such as repetitive trills or quavers. Human vocal tract articulation is much faster, and humans are able to produce multiple sounds on a single breath movement, inhalation or exhalation. The unique form of the tongue within the vocal tract in humans is considered to be a key factor in the speech-related flexibility of supralaryngeal vocal tract.

The major medium for the transmission of human language is vocalization, or speech. Humans use rapid, highly variable, extended sound sequences to transmit the complex information content of language. Speech is a very efficient communication medium: it costs little energetically, it does not require visual contact with the intended receiver(s), and it can be carried out simultaneously with separate manual and other tasks. Although the vocal communication systems of some birds and other mammals, such as cetaceans, may resemble important aspects of human speech, none is as complex, nor as capable of transmitting information, as human speech‐propelled language. Certainly, our closest relatives, the apes and other primates, demonstrate nothing close to this unique human form of communication. Human speech production involves a range of physical features which may have evolved as specific adaptations for this purpose; alternatively, they evolved as exaptations, commandeering existing features. Combining knowledge of the anatomical and physiological basis of human speech production, comparisons with other primate species, and information from the human fossil record, it is possible to form an outline framework for the evolution of human speech capabilities, the features concerned, the likely timing and sequence in which they arose, and the possible combination of adaptations and exaptations involved—the what, when, and why of speech evolution.

All mammalian vocalizations are produced similarly, involving features that primarily evolved for respiration or ingestion. Sounds are produced using the flow of air inhaled through the nose or mouth, or expelled from the lungs. Unvoiced sounds are produced without the involvement of the vocal folds of the larynx. They entail pressurizing the airflow by temporary restriction of the vocal tract at some point(s) along its length. The turbulence of the released air produces either an aperiodic noise, such as a burst or hiss, or, under special conditions, it may produce a periodic sound such as a whistle. For voiced or phonated sounds, the vocal folds at the glottis of the larynx (a structure which first evolved at the top of the trachea to prevent water entering the lungs in aquatic creatures) are held taut, and the air flow needs to be powerful enough to cause the vocal folds to vibrate. This cuts the air flow into a chain of ‘air puffs’, or a periodic sound wave, perceived by the ear as sound at a pitch equivalent to the air puff frequency; this is known as the fundamental frequency or F 0 , and it varies with the length and tension of the vocal folds. Voiced sounds may be modified further by so‐called gestural articulations of the supralaryngeal vocal tract produced by positions or movements of articulatory structures such as the tongue and lips, both primarily involved in ingestion. Mammalian vocalizations therefore require coordination of the articulation of the supralaryngeal vocal tract with the flow of air, in or out. For phonated sounds, an extensive series of harmonics above F 0 is produced by resonance. These series are filtered by the shape and size of the vocal tract, resulting in the retention of some parts of the series, and diminution or deletion of others, in the emitted vocalization. Unvoiced vocalizations generally have less structured acoustic features and broad bands of emitted frequencies. What distinguishes human speech from the vocalizations of other species is the extraordinary range of acoustic variation involved, produced by an enormous variety of gestural articulations of the vocal tract, together with intricate manipulations of the larynx and other respiratory structures. Rather than utilizing the air flow of both inspirations and expirations, human speech is also produced almost entirely on expired air, released in extended, highly controlled expirations.

More than 100 different sound units or phonemes found in human languages are recognized in the International Phonetic Alphabet, together with a further array of major variant types. Each sound unit is acoustically distinctive (Fant 1960 ), as depicted in spectrograms, in which emitted sound frequencies and their amplitudes are plotted against time. Phonemes vary with different relative timing of the start of phonation and of vocal tract constriction, different speeds of movement and combinations of vocal tract articulators, different intonation changes produced in the larynx or by the lungs; sounds may be breathy, creaky, nasal, or aspirated, and so the list goes on. Different languages use different subsets of phonemes.

Phonemes comprise consonants and vowels, which form the building blocks of syllables. Consonants, voiced or unvoiced, involve the complete or near complete obstruction and release of airflow through the vocal tract, which produces characteristic spectrum profiles or envelopes of sound frequencies emitted over time (Fant 1960 ). Vowels always involve phonation, and filtering through different vocal tract constrictions produced by gestures of the tongue, without complete obstruction. They are distinguished by their combinations of formants (Fant 1960 ), which are sharp peaks in the frequency ranges above F 0 emitted following filtration, known as F 1 , F 2 , etc.; typically, different vowels within a language can be characterized by the first two formants. The perception of vowels is not dependent on their absolute formant frequencies, but rather their relative values, normalized by the listener according to the typical frequency levels of a particular individual speaker, be they generally higher or lower pitched, the differences resulting from a shorter or longer vocal tract.

The range and variation of human speech sounds, the different subsets utilized in hundreds of languages, and how they are produced anatomically and physiologically, have been superbly documented in an extraordinary compendium by Ladefoged and Maddieson ( 1996 ). For consonants, they describe how nine independent, moveable, soft tissue articulators can be distinguished: lips; tongue—tip, blade, underblade, front, back, root; epiglottis; and glottis. These move to constrict or block the vocal tract at 11 main articulation points, or more accurately zones: lips, incisor teeth, different points along the palate, the velum or soft palate, and the uvula (the skin flap hanging from the velum), the pharynx or throat, the epiglottis, and the glottis. Together these produce 17 different categories of articulatory gestures, whose precise formation varies in different languages and dialects. Consonants are further differentiated into stops, nasals, fricatives, laterals, rhotics, and clicks, according to whether they involve, respectively, momentary complete stoppage of airflow by vocal tract obstruction, mouth closure and nasal‐only airflow, a turbulent airstream, midline tract closure limited with lateral airflow around the partial obstruction, tongue trills and related movements, or two points of vocal tract closure trapping air with subsequent articulator movement increasing the trapped air volume and hence decreasing pressure prior to its sudden release. Vowel production involves subtle tongue‐shaping in the oral or pharyngeal cavities, resulting in different points of vocal tract constriction, and hence different formant combinations.

It became evident early in attempts to teach apes to speak that our closest living relatives are not capable of the intricate articulatory manoeuvres of the upper respiratory tract which underlie the enormous range of human speech sounds. Recent evidence from Diana monkeys suggests that vocal tract articulation in non‐human primates may not be as severely limited as previously thought (Riede et al. 2005 ). However, it seems improbable that capabilities so useful to human communication would not have been exploited more fully if they existed in other species, and it is therefore likely that the human capacity for the production of highly varied speech sounds is unique among primates.

Human sound sequences are also much more rapid than those of non‐human primates, except for very simple sequences such as repetitive trills or quavers. Human vocal tract articulation is much faster, and humans are able to produce multiple sounds on a single breath movement, inhalation or exhalation. Most non‐human sound sequences, such as chimpanzee pant‐hoots and other vocalizations (Marler and Tenaza 1977 ), are produced on successive inspirations and expirations. Commonly each component sound of such sequences (e.g. the pant, or the hoot of the chimpanzee call) can only be produced on either an inhalation or an exhalation, which also restricts sound sequence combinations.

The laryngeal air sacs present in some non‐human primate species enable them to produce slightly more complex sound sequences on single breath movements, either through additional breath movements in and out of the sacs, or by vibration of the vocal lip at the opening of the sacs into the larynx (e.g. bitonal scream of siamangs; Haimoff 1983 ). Humans do not possess air sacs, and instead produce complex sound sequences by the intricate manipulation of airflow within individual exhalations, freed much more than any non‐human primate from the restrictions of vocalizations tied to breath movements (Hewitt et al. 2002 ). Overall, humans are able to produce sound sequences of up to about 30 sound units per second (P. Lieberman et al. 1992 ). Maximum sound production rates for non‐human primates are typically only 2–3 per second, extending to 5 per second with the involvement of air sacs (MacLarnon and Hewitt 1999 ).

Human speech also demonstrates further flexibility through an enhanced ability to control breathing, the airflow itself, compared with non‐human primates (MacLarnon and Hewitt 1999 , 2004 ). First, humans speak on very extended exhalations, interspersed with quick inhalations, compared with much more even breathing cycles during quiet breathing; non‐human primates appear not to be able to distort their breathing cycles so markedly. During normal speech, humans typically utilize exhalations of 4–5 seconds (Hoit et al. 1994 ), extending up to more than 12 seconds (Winkworth et al. 1995 ), whereas the longest calls given on single breath movements in non‐human primates are only about 5 seconds (MacLarnon and Hewitt 1999 ). Calibrating these measures, taking into account the faster quiet breathing rates of smaller animals, the maximum duration of human speech exhalations is more than 7 times that during quiet breathing. In non‐human primates, the normal maximum duration of exhalations during vocalization is only 2–3 times that during quiet breathing. The exceptions to this are species with air sacs, such as howler monkeys and gibbons, which can extend exhalations to 4–5‐fold their duration during quiet breathing. Again, humans do not possess air sacs, an apparent alternative to control of pulmonary air release for extending call exhalation length, though one that does not enable the very subtle control of respiratory airflow of human speech (Hewitt et al. 2002 ).

22.1 Sound articulation

The unique form of the tongue within the vocal tract in humans is considered to be a key factor in the speech‐related flexibility of our supralaryngeal vocal tract (P. Lieberman 1984 ). In mammals, the tongue is typically a flat muscular structure lying largely within the oral cavity, anchored posteriorly by its attachment to the hyoid bone, which lies just below oral level in the pharynx, immediately above the larynx. The primary function of the tongue is to move food around the mouth for mastication, and posteriorly for swallowing. In humans, however, the tongue is a curved structure, lying part horizontally in the oral cavity and part vertically down an extended pharynx, where it attaches to a much lower hyoid, just above a descended larynx. The horizontal (oral) and vertical (pharyngeal) portions of the human supralaryngeal tract (SVT H and SVT V ) are equal in length, compared with other species in which SVT H is substantially longer. Greatly because of its curvature, movement of the human tongue, together with jaw movements, can vary the cross‐sectional area of each of the two tubes of our vocal tract independently by a factor of approximately ten, providing a very broad range of articulatory gestures, and very variable resultant formants of emitted sound. The 1:1 ratio of SVT H :SVT V , with a sharp bend between the two, is notably important for the production of three vowels, designated phonetically [i], [u], and [a]. These vowels are particularly easily distinguished, with very low perceptual error rates, by their F1, F2 combinations, which lie at the outer limits of the acoustic vowel space, and [i], followed by [u], is the most reliable and commonly used sound unit for vocal tract normalization. The tongue positions for production of the three vowels utilize the angle at the midpoint of the human vocal tract to produce abrupt discontinuities in the cross‐sectional areas of the tube. Because the angle is sharp, the articulatory gestures involved do not have to be performed with particular accuracy for consistent, distinctive acoustic results, making these vowels marked examples of the quantal nature of human speech sounds (Stevens 1972 ). Perhaps consequently, they are the most common vowels in the world's languages (Ladefoged and Maddieson 1996 ).

Humans are not completely unique in having a descended larynx; species including dog, goat, pig, and tamarin lower the larynx during loud calls (Fitch 2001b ). Several deer have a permanently lowered larynx, which may temporarily be lowered further during male roars (Fitch and Reby 2001 ); large cats are apparently similar (Weissengruber et al. 2002 ). However, laryngeal descent is rarely accompanied by descent of the hyoid; hence the tongue remains horizontal in the oral cavity, and cannot act as a pharyngeal articulator (P. Lieberman 2007 ). Temporary laryngeal descent is also much less disruptive of other functions. In humans, because of marked, permanent laryngeal descent, simple contact between the epiglottis and velum is no longer possible, disrupting the normal mammalian separation of the respiratory and digestive tracts during swallowing, and increasing the risk of choking. Permanent laryngeal descent is thus a very different evolutionary development. Nishimura et al. ( 2006 ) have demonstrated that the larynx does descend to some extent during development in chimpanzees, followed by hyoidal descent. However, only humans have evolved permanent, major, laryngeal descent, with associated hyoidal descent, resulting in a curved tongue, and a two‐tube vocal tract with 1:1 proportions. It is not laryngeal descent per se that is crucial to human speech capabilities, but rather a suite of factors in the shape and proportions of the supralaryngeal vocal tract and tongue (P. Lieberman 2007 ).

Considerable efforts have been made to determine when the two‐tube vocal tract evolved in our ancestors, using indirect means, as its soft tissue structures do not fossilize. Reconstruction of the fossil hominin tract was first attempted by Philip Lieberman and Crelin ( 1971 ), using basicranial and mandibular characteristics, followed by Laitman and colleagues (e.g. 1979), who used the basicranial angle, or flexion of the skull base. However, Daniel Lieberman and McCarthy ( 1999 ) recently demonstrated, using radiographic series, that human laryngeal descent is not linked ontogenetically to the development of basicranial flexion. So, reconstruction of the supralaryngeal tract is not possible from basicranial form, and much previous work on the speech articulation capabilities of fossil hominins was therefore flawed, as P. Lieberman ( 2007 ) has fully accepted. In addition, D. Lieberman et al. ( 2001 ) showed that during postnatal descent of the hyoid and larynx in humans, the relative vertical positions of the hyoid, mandible, hard palate and larynx are held more or less constant. However, the ratio SVT H :SVT V changes during development, as a result of differential growth patterns of the total oral and pharyngeal lengths, and only reaches 1:1 from about 6–8 years. Together these results indicate that the descent of the hyolaryngeal structures is primarily constrained to maintain muscular function in relation to mandibular movement for swallowing; speech‐related factors are not maximized until well into childhood, matching the gradual ontogenetic development of acoustically accurate speech production (P. Lieberman 1980 ). Various possible exaptive explanations for why humans evolved their unique vocal tract configuration have been proposed. For example, obligate bipedalism required a more forward position of the spine under the skull, possibly reducing the space available in the upper throat, so squeezing the hyoid and larynx down the pharynx; increased carnivory in early Homo was associated with reduced jaw size and reduced oral cavity length, possibly requiring a compensatory increase in pharyngeal length (Negus 1949 ; Aiello 1996 ).

Recently, D. Lieberman and colleagues (e.g. 2002) have produced substantial new evidence on the integrated evolution of many modern human cranial features, providing a more comprehensive basis for exploring the evolution of the human vocal tract. They showed that a small number of developmental shifts distinguish modern human crania from those of our predecessors, including two—a more flexed basicranium and reduction in face size—which result in a shortening of SVT H , contributing to the attainment of an SVT H :SVT V ratio of 1:1. D. Lieberman ( 2008 ) suggested possible adaptational bases for these shifts, such as temporal lobe increase for enhanced cognitive processing including language, increasing basicranial flexion; increased meat consumption and technologically enhanced food processing including cooking, resulting in facial reduction; endurance running, building on obligate bipedalism, involving facial reduction for improved head stabilization; direct selection for speech capabilities, driving a decrease in oral cavity length, involving facial reduction and/or basicranial flexion, to produce a 1:1 SVT H :SVT V ratio. In other words, a suite of factors may have affected SVT H , and hence played a part in the evolution of the modern human capability for quantal speech. The other component in the evolution of a 1:1 ratio, an increase in SVT V , may have been directly selected for enhanced speech capabilities, so counterbalancing the negative impact of increased choking risk. However, this would not have been advantageous prior to substantial decrease in SVT H , because a long SVT V would require laryngeal descent into the thorax, producing muscular orientations that would compromise functional swallowing. Rather than major, coordinated shifts in both vocal tract parameters occurring with the evolution of modern humans, I think it more probable that other factors, earlier in human evolution, produced descent of the hyolaryngeal complex, and an increase in SVT V . From this exaptive basis, final reduction in SVT H, with the evolution of modern human cranial shape, could be adaptive for quantal speech. As outlined above, maintenance of functional swallowing is central to human developmental hyolaryngeal descent, which only becomes advantageous for speech articulation later in childhood. This, too, is congruent with the suggestion that hyolaryngeal descent resulted from earlier evolutionary change. The most likely candidate is the evolution of bipedalism, involving reconfiguration of neck structures, in Homo erectus . Jaw length also reduced in this species, associated with changing diet and food processing. The use of more complex vocalizations for communication may have begun to increase at the same time, alongside brain size and presumed social complexity (Aiello 1996 ).

As well as its curved shape, other features of the tongue have also been explored for their potential contribution to human speech articulation. Duchin ( 1990 ) drew attention to the greater manoeuvrability of the human tongue compared with apes. Jaw reduction produces a shorter, more controllable tongue, and hyoidal descent angles the tongue, increasing mechanical advantage. Takemoto ( 2008 ) showed that chimpanzee and human tongues have the same detailed internal topology, a muscular hydrostat formation (Kier and Smith 1985 ), which enables elongation, shortening, thinning, fattening, and twisting of the tongue for moving food around the mouth and for swallowing. However, the overall curved shape of the human tongue, compared with the flat chimpanzee form, means the same internal structures are arranged radially in humans, compared with linearly in apes, which increases the degrees of freedom for tongue deformation (Takemoto 2008 ). Hence, the dietary and other changes from early Homo through to modern humans provided the potential for enhanced control of speech articulation gestures through exaptive realignment of both external and internal tongue features.

The lips are second only to the tongue in their importance as human speech articulators. They are particularly important for the production of two major consonant groups, stops and fricatives (the former being the only consonant type to occur in all languages), and also in vowel production (Ladefoged and Maddieson 1996 ). In typical mammals, the face is dominated by a prominent snout housing major structures of the highly developed olfactory sense, which extend onto the face, in the form of the rhinarium, or wet nose. Within primates, the evolution of the haplorhines (tarsiers, monkeys, and apes) involved a shift to diurnal activity from the typical mammalian nocturnal pattern retained by strepsirhines (lemurs and lorises). With this came increased specialization of the visual sense, and an associated reduction in olfaction. The snout reduced, and the rhinarium was lost. As a result, the facial and lip muscles became less constrained and were co‐opted for facial expressions. Haplorhines evolved thicker lips (Schön Ybarra 1995 ), presumably to enhance this function. Hence, the evolution of mobile, muscular lips, so important to human speech, was the exaptive result of the evolution of diurnality and visual communication in the common ancestor of haplorhines. There is a lack of evidence as to whether there have been further adaptational developments in the lips during human evolution, or whether there have been changes in some other articulators, such as the velum or the epiglottis.

To date, there has been one attempt to investigate the comparative innervation of human vocal tract articulators. Kay et al. ( 1998 ) used the size of the hypoglossal canal in the base of the skull to estimate the relative number of nerve fibres in the hypoglossal nerve, which is a major innervator of the tongue. Their results suggested that Middle Pleistocene hominins and Neanderthals had modern human levels of tongue innervation, substantially greater than found in australopithecines and apes, and hence, they suggested, human‐like speech‐related tongue control had evolved by this time. However, DeGusta et al. ( 1999 ) demonstrated that hypoglossal canal and nerve sizes are not correlated, and Jungers et al. ( 2003 ) accepted that the canal size therefore offers no evidence about the timing of human speech evolution. Split second coordination between the highly flexible movements of the human speech articulators is required for human speech, as well as coordination with laryngeal movements affecting phonation. Different sounds result, for example, if the vocal cords start vibrating slightly before, at the same time, or slightly after an articulatory gesture. It seems likely that at least some increase in neural control has evolved in humans for speech articulation, even if empirical evidence is presently lacking.

22.2 Respiratory control

Humans have enhanced control of breathing compared with non‐human primates, which they use to extend exhalations and shorten inhalations during speech, as well as to modulate loudness. Humans are not constrained to produce vocalizations that fade as the lungs deflate. They can also vary the volume of air released through a phrase to emphasize particular words or syllables. In addition, variation in subglottal air pressure can affect intonation patterns. Enhanced breathing control therefore contributes to the human ability to produce fast sound sequences, and to generate a whole variety of language‐specific patterns and meanings, communicated through the intonation and emphasis of phrases or specific syllables. Much of this needs to be tied to cognitive intention, involving complex neural communication and feedback (MacLarnon and Hewitt 1999 ).

Control of subglottal pressure is key to human speech breathing control. During speech breathing, intercostal and anterior abdominal muscles are recruited to expand the thorax and draw air into the lungs, and to control gravitational recoil and hence the release of air as the lungs deflate. This is similar to quiet breathing, except that the diaphragm has a very limited role in speech breathing. It also differs from muscle recruitment during non‐human primate vocalizations, which does involve the diaphragm, and has only a limited role for intercostal muscles (e.g. Jürgens and Schriever 1991 ). The specific muscle movements required vary according to the volume of the lungs and other actions undertaken simultaneously (MacLarnon and Hewitt 1999 ). Overall, the fineness of control required of the intercostal muscles during human speech has been likened to that of the small muscles of the hand (Campbell 1968 ).

There is evidence, from an increase in spinal cord grey matter in the thoracic region, that humans have markedly greater innervation of the intercostal and anterior abdominal muscles compared with non‐human primates (MacLarnon 1993 ). Spinal cord dimensions are well correlated with those of its bony encasement, the vertebral canal. Evidence from fossil hominins demonstrates that enlargement of the canal, and therefore the cord, was not present in australopithecines and Homo erectus , but was present in Neanderthals and early modern humans (MacLarnon and Hewitt 1999 ). The function requiring enhanced neurological control therefore evolved in later human evolution. Of all the functions of the intercostal muscles, including maintenance of body posture for bipedal locomotion, vomiting, coughing, defecation, and breathing control, only enhanced breathing control for speech both requires substantial neurological control and fits the evolutionary timing constraints. It appears, therefore, that enhanced breathing control for speech was absent in Homo erectus , and present in the common ancestor of Neanderthals and modern humans, in the later Middle Pleistocene (MacLarnon and Hewitt 1999 , 2004 ).

As outlined above, human breathing control is not aided by the presence of air sacs, which can provide additional re‐breathed air for the extension of exhalations, without the risk of hyperventilation from excess oxygen intake (Hewitt et al. 2002 ). Larger ape species all possess laryngeal air sacs, so they were presumably lost at some point during human evolution. Air sacs abut against the hyoid bone where they produce characteristic indentions. The australopithecine hyoid from Dikika demonstrates the presence of air sacs (Alemseged et al. 2006 ), whereas hyoids from Homo heidelbergensis at Atapuerca, and a specimen from Castel di Guido dated to 400,000 years ago, as well as Neanderthals from El Sidrón and Kebara (Arensburg et al. 1990 ; Capasso et al. 2008 ; Martínez et al. 2008 ), show that air sacs had been lost by some point in the Middle Pleistocene. One possibility is that this occurred when the human thorax altered from the funnel‐shape of australopithecines, to the barrel‐shape of Homo erectus , as, in apes, air sacs extend into the thorax. It therefore quite probably occurred prior to the evolution of human speech‐breathing control, and it may also have been a necessary prerequisite stage.

The mammalian larynx, which protects the entrance to the lungs during swallowing, comprises a series of three sets of articulating cartilages connected by ligaments and membranes. Some mammal species retain a non‐valvular larynx, in which occlusion involves a simple muscular sphincter; other species have a valvular larynx, in which a mechanical valve provides for closure at the glottis. Based on the distribution of the valvular form, including its greatest development in primates, Negus ( 1949 ) proposed that the valvular larynx is a locomotor adaptation, enabling greater stabilization of the thorax in species with independent use of the forelimbs, through build up of air pressure below a closed glottis. Humans share with gibbons an extreme ability to close the glottis; other primates cannot completely close it off as the inner edges of the vocal processes of their arytenoid cartilages are curved, and when brought together, a small hiatus intervocalis always remains (Schön Ybarra 1995 ). Most likely humans lost the hiatus intervocalis independently from gibbons, as it is retained in living great apes. Gibbons may have evolved complete closure as an adaptation to brachiation. Bipedal humans use the capability of building up high subglottal pressure while lifting heavy objects with their arms, and in forceful coughing, which is particularly important with upright posture (Aiello and Dean 1990 ). In addition, for human speech, substantial subglottal air pressure is required to fuel very long exhalations. Complete glottal closure enhances the ability to control the pitch or intonation (Kelemen 1969 ), something which gibbons use in their songs, and humans use in speech, although it is unclear whether subglottal air pressure, or movements of the laryngeal cricothyroid muscle are more important in human control of intonation (Borden et al. 2003 ). Overall, humans probably lost the hiatus intervocalis as an adaptation to bipedalism, providing an exaptation for speech. Further to this, the membranous part of the vocal folds of humans is less sharp‐edged than in other primates (Negus 1929 ). This may be a direct adaptation for the production of more melodious sounds, selected for at some point after the locomotor‐associated function of the larynx altered in humans, with the evolution of exclusive bipedality in Homo erectus (Aiello 1996 ).

22.3 Evolutionary framework

Diet and technology‐related changes through human evolution, from the time of early Homo , have produced decreases in jaw and tongue length exaptive for the evolution of human speech capabilities. In addition to these, a three‐stage framework for the major features of human speech evolution can tentatively be proposed: first, the evolution of obligate bipedalism in Homo erectus produced the exaptations of laryngeal descent, and the loss of air sacs and the hiatus intervocalis; secondly, during the Middle Pleistocene, human speech breathing control evolved as a specific speech adaptation; thirdly, with the evolution of modern humans, the optimal vocal tract proportions (1:1) were evolved adaptively. Further details are summarized in Table 22.1 , together with suggested speech capabilities for each stage of the evolutionary framework.

Acknowledgements

I would like to thank Kathleen Gibson and Maggie Tallerman for the invitation to contribute to this volume, and for their very helpful editing. My interest in the evolution of human speech was first stimulated by stumbling on evidence for the evolution of human breathing control working with Gwen Hewitt. This paper builds on a lecture prepared for the Language Origins Society, thanks to an invitation from Bernard Bichakjian.

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2.1 How Humans Produce Speech

Phonetics studies human speech. Speech is produced by bringing air from the lungs to the larynx (respiration), where the vocal folds may be held open to allow the air to pass through or may vibrate to make a sound (phonation). The airflow from the lungs is then shaped by the articulators in the mouth and nose (articulation).

Check Yourself

Video script.

The field of phonetics studies the sounds of human speech.  When we study speech sounds we can consider them from two angles.   Acoustic phonetics ,  in addition to being part of linguistics, is also a branch of physics.  It’s concerned with the physical, acoustic properties of the sound waves that we produce.  We’ll talk some about the acoustics of speech sounds, but we’re primarily interested in articulatory phonetics , that is, how we humans use our bodies to produce speech sounds. Producing speech needs three mechanisms.

The first is a source of energy.  Anything that makes a sound needs a source of energy.  For human speech sounds, the air flowing from our lungs provides energy.

The second is a source of the sound:  air flowing from the lungs arrives at the larynx. Put your hand on the front of your throat and gently feel the bony part under your skin.  That’s the front of your larynx . It’s not actually made of bone; it’s cartilage and muscle. This picture shows what the larynx looks like from the front.

This next picture is a view down a person’s throat.

What you see here is that the opening of the larynx can be covered by two triangle-shaped pieces of skin.  These are often called “vocal cords” but they’re not really like cords or strings.  A better name for them is vocal folds .

The opening between the vocal folds is called the glottis .

We can control our vocal folds to make a sound.  I want you to try this out so take a moment and close your door or make sure there’s no one around that you might disturb.

First I want you to say the word “uh-oh”. Now say it again, but stop half-way through, “Uh-”. When you do that, you’ve closed your vocal folds by bringing them together. This stops the air flowing through your vocal tract.  That little silence in the middle of “uh-oh” is called a glottal stop because the air is stopped completely when the vocal folds close off the glottis.

Now I want you to open your mouth and breathe out quietly, “haaaaaaah”. When you do this, your vocal folds are open and the air is passing freely through the glottis.

Now breathe out again and say “aaah”, as if the doctor is looking down your throat.  To make that “aaaah” sound, you’re holding your vocal folds close together and vibrating them rapidly.

When we speak, we make some sounds with vocal folds open, and some with vocal folds vibrating.  Put your hand on the front of your larynx again and make a long “SSSSS” sound.  Now switch and make a “ZZZZZ” sound. You can feel your larynx vibrate on “ZZZZZ” but not on “SSSSS”.  That’s because [s] is a voiceless sound, made with the vocal folds held open, and [z] is a voiced sound, where we vibrate the vocal folds.  Do it again and feel the difference between voiced and voiceless.

Now take your hand off your larynx and plug your ears and make the two sounds again with your ears plugged. You can hear the difference between voiceless and voiced sounds inside your head.

I said at the beginning that there are three crucial mechanisms involved in producing speech, and so far we’ve looked at only two:

• Energy comes from the air supplied by the lungs.
• The vocal folds produce sound at the larynx.
• The sound is then filtered, or shaped, by the articulators .

The oral cavity is the space in your mouth. The nasal cavity, obviously, is the space inside and behind your nose. And of course, we use our tongues, lips, teeth and jaws to articulate speech as well.  In the next unit, we’ll look in more detail at how we use our articulators.

So to sum up, the three mechanisms that we use to produce speech are:

• respiration at the lungs,
• phonation at the larynx, and
• articulation in the mouth.

Essentials of Linguistics Copyright © 2018 by Catherine Anderson is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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Speech in Linguistics

• An Introduction to Punctuation
• Ph.D., Rhetoric and English, University of Georgia
• M.A., Modern English and American Literature, University of Leicester
• B.A., English, State University of New York

In linguistics , speech is a system of  communication  that uses spoken words  (or sound symbols ). 

The study of speech sounds (or spoken language ) is the branch of linguistics known as phonetics . The study of sound changes in a language is phonology . For a discussion of speeches in rhetoric and oratory , see Speech (Rhetoric) .

Etymology:  From the Old English, "to speak"

Studying Language Without Making Judgements

• "Many people believe that written language is more prestigious than spoken language--its form is likely to be closer to Standard English , it dominates education and is used as the language of public administration. In linguistic terms, however, neither speech nor writing can be seen as superior. Linguists are more interested in observing and describing all forms of language in use than in making social and cultural judgements with no linguistic basis." (Sara Thorne, Mastering Advanced English Language , 2nd ed. Palgrave Macmillan, 2008)

Speech Sounds and Duality

• "The very simplest element of speech --and by 'speech' we shall henceforth mean the auditory system of speech symbolism, the flow of spoken words--is the individual sound, though, . . . the sound is not itself a simple structure but the resultant of a series of independent, yet closely correlated, adjustments in the organs of speech." ( Edward Sapir , Language: An Introduction to the Study of Speech , 1921)
• "Human language is organized at two levels or layers simultaneously. This property is called duality (or 'double articulation'). In speech production, we have a physical level at which we can produce individual sounds, like n , b and i . As individual sounds, none of these discrete forms has any intrinsic meaning . In a particular combination such as bin , we have another level producing a meaning that is different from the meaning of the combination in nib . So, at one level, we have distinct sounds, and, at another level, we have distinct meanings. This duality of levels is, in fact, one of the most economical features of human language because, with a limited set of discrete sounds, we are capable of producing a very large number of sound combinations (e.g. words) which are distinct in meaning." (George Yule, The Study of Language , 3rd ed. Cambridge University Press, 2006)

Approaches to Speech

• "Once we decide to begin an analysis of speech , we can approach it on various levels. At one level, speech is a matter of anatomy and physiology: we can study organs such as tongue and larynx in the production of speech. Taking another perspective, we can focus on the speech sounds produced by these organs--the units that we commonly try to identify by letters , such as a 'b-sound' or an 'm-sound.' But speech is also transmitted as sound waves, which means that we can also investigate the properties of the sound waves themselves. Taking yet another approach, the term 'sounds' is a reminder that speech is intended to be heard or perceived and that it is therefore possible to focus on the way in which a listener analyzes or processes a sound wave." (J. E. Clark and C. Yallop, An Introduction to Phonetics and Phonology . Wiley-Blackwell, 1995)

Parallel Transmission

• "Because so much of our lives in a literate society has been spent dealing with speech recorded as letters and text in which spaces do separate letters and words, it can be extremely difficult to understand that spoken language simply does not have this characteristic. . . . [A]lthough we write, perceive, and (to a degree) cognitively process speech linearly--one sound followed by another--the actual sensory signal our ear encounters is not composed of discretely separated bits. This is an amazing aspect of our linguistic abilities, but on further thought one can see that it is a very useful one. The fact that speech can encode and transmit information about multiple linguistic events in parallel means that the speech signal is a very efficient and optimized way of encoding and sending information between individuals. This property of speech has been called parallel transmission ." (Dani Byrd and Toben H. Mintz, Discovering Speech, Words, and Mind . Wiley-Blackwell, 2010)

Oliver Goldsmith on the True Nature of Speech

• "It is usually said by grammarians , that the use of language is to express our wants and desires; but men who know the world hold, and I think with some show of reason, that he who best knows how to keep his necessities private is the most likely person to have them redressed; and that the true use of speech is not so much to express our wants, as to conceal them." (Oliver Goldsmith, "On the Use of Language." The Bee , October 20, 1759)

Pronunciation: SPEECH

• Duality of Patterning in Language
• Phonology: Definition and Observations
• What Is Phonetics?
• Definition and Examples of Productivity in Language
• Spoken English
• Definition of Voice in Phonetics and Phonology
• Phonological Segments
• What Are Utterances in English (Speech)?
• Grapheme: Letters, Punctuation, and More
• What Is a Phoneme?
• Phoneme vs. Minimal Pair in English Phonetics
• Connected Speech
• What Is Graphemics? Definition and Examples
• 10 Titillating Types of Sound Effects in Language
• Assimilation in Speech

The Parts of Human Speech Organs & Their Definitions

Types of Phonetics

Imagine being unable to verbally respond to a verbal greeting. Thinking about the ability to speak as an important part of your day may not cross your mind. If that speech ability was taken away, you might find yourself unable to communicate not only basic speech but also emotional responses like fear, confusion or anxiety. Although you may not give your speech organs much thought, they are integrally tied to how you function. From the lungs to the mouth, the organs of speech and their function in sound production and speech play important roles in many aspects of your life.

Breathing and Speaking Connections

Looking at the speech mechanism and organs of speech begins with the vital lungs. The lungs are located in the chest cavity and expand and contract to push air out of the mouth. Simple airflow is not enough to produce speech. The airflow must be modified by other speech organs to be more than just respiration. When you exhale, air moves out of your lungs through your windpipe or trachea. At the top of the trachea is one of the other primary organs of speech: the larynx or voice box.

Vibrations of the Larynx

Three more parts of the speech mechanism and organs of speech are the larynx, epiglottis and vocal folds. The larynx is covered by a flap of skin called the epiglottis. The epiglottis blocks the trachea to keep food from going into your lungs when you swallow. Across the larynx are two thin bands of tissue called the vocal folds or vocal cords. Depending on how the folds are positioned, air coming through the trachea makes them vibrate and buzz. These vibrations are called a "voiced" or soft sound. Placing finger tips over the Adam's apple or larynx at the front of your neck while humming makes it possible to feel the vocal fold vibration.

Articulators of Speech

The inside of your mouth is also called the oral cavity and controls the shape of words. At the back of the oral cavity on the roof of the mouth is the soft palate or velum. When you pronounce oral sounds, such as "cat" or "bag," the velum is located in the up position to block air flow through the nasal cavity. When you pronounce nasal sounds, such as "can" or "mat," the velum drops down to allow air to pass through the nasal cavity. In front of the velum is the hard palate. Your tongue presses or taps against the hard palate when you pronounce certain words, such as "tiptoe." Developmental or physical issues related to speech organs that are articulators of speech can result in a need for speech therapy.

Teeth, Tongue and Lips

Say "Thank you." Feel how your tongue presses against the inside of your front teeth. The convex area directly behind your teeth is known as the teeth ridge. For the purpose of linguistics, the tongue is divided into three regions: the blade, front and back. The tip of the tongue, which touches the teeth ridge, is called the blade. The middle of the tongue, which lines up with the hard palate, is called the front of the tongue. Finally, beneath the soft palate is the back of the tongue. The final speech organ is the most visible and obvious: the lips. Your lips influence the shape of the sounds leaving the oral cavity. Each of these organs of speech and their definitions is important to the process of speech, articulation and expressions through sounds.

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Speech Techniques for High School

• The University of Iowa: Three Parts of Speech
• Aston University: How Sound is Produced
• The Scientist: Why Human Speech is Special

Carolyn Robbins began writing in 2006. Her work appears on various websites and covers various topics including neuroscience, physiology, nutrition and fitness. Robbins graduated with a bachelor of science degree in biology and theology from Saint Vincent College.

• Question and Answer
• Open access
• Published: 24 July 2017

Q&A: What is human language, when did it evolve and why should we care?

• Mark Pagel 1  

BMC Biology volume  15 , Article number:  64 ( 2017 ) Cite this article

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Human language is unique among all forms of animal communication. It is unlikely that any other species, including our close genetic cousins the Neanderthals, ever had language, and so-called sign ‘language’ in Great Apes is nothing like human language. Language evolution shares many features with biological evolution, and this has made it useful for tracing recent human history and for studying how culture evolves among groups of people with related languages. A case can be made that language has played a more important role in our species’ recent (circa last 200,000 years) evolution than have our genes.

What is special about human language?

Human language is distinct from all other known animal forms of communication in being compositional . Human language allows speakers to express thoughts in sentences comprising subjects, verbs and objects—such as ‘I kicked the ball’—and recognizing past, present and future tenses. Compositionality gives human language an endless capacity for generating new sentences as speakers combine and recombine sets of words into their subject, verb and object roles. For instance, with just 25 different words for each role, it is already possible to generate over 15,000 distinct sentences. Human language is also referential , meaning speakers use it to exchange specific information with each other about people or objects and their locations or actions.

What is animal ‘language’ like?

Animal ‘language’ is nothing like human language. Among primates, vervet monkeys ( Chlorocebus pygerythrus ) produce three distinct alarm calls in response to the presence of snakes, leopards and eagles [ 1 ]. A number of parrot species can mimic human sounds, and some Great Apes have been taught to make sign language gestures with their hands. Some dolphin species seem to have a variety of repetitive sound motifs (clicks) associated with hunting or social grouping. These forms of animal communication are symbolic in the sense of using a sound to stand in for an object or action, but there is no evidence for compositionality, or that they are truly generative and creative forms of communication in which speakers and listeners exchange information [ 2 ].

Instead non-human animal communication is principally limited to repetitive instrumental acts directed towards a specific end, lacking any formal grammatical structure, and often explainable in terms of hard-wired evolved behaviours or simple associative learning [ 2 ]. Most ape sign language, for example, is concerned with requests for food. The trained chimpanzee Nim Chimpsky’s longest recorded ‘utterance’, when translated from sign language, was ‘give orange me give eat orange me eat orange give me eat orange give me you’ [ 3 ]. Alarm calls such as observed in the vervet monkeys often evolve by kin-selection to protect one’s relatives, or even selfishly to distract predators away from the caller. Hunting and social group communications can be explained as learned coordinating signals without ‘speakers’ knowing why they are acting as they are.

When did human language evolve?

No one knows for sure when language evolved, but fossil and genetic data suggest that humanity can probably trace its ancestry back to populations of anatomically modern Homo sapiens (people who would have looked like you and me) who lived around 150,000 to 200,000 years ago in eastern or perhaps southern Africa [ 4 , 5 , 6 ]. Because all human groups have language, language itself, or at least the capacity for it, is probably at least 150,000 to 200,000 years old. This conclusion is backed up by evidence of abstract and symbolic behaviour in these early modern humans, taking the form of engravings on red-ochre [ 7 , 8 ].

The archaeological record reveals that about 40,000 years ago there was a flowering of art and other cultural artefacts at modern human sites, leading some archaeologists to suggest that a late genetic change in our lineage gave rise to language at this later time [ 9 ]. But this evidence derives mainly from European sites and so struggles to explain how the newly evolved language capacity found its way into the rest of humanity who had dispersed from Africa to other parts of the globe by around 70,000 years ago.

Could language be older than our species?

Ancient DNA reveals us to be over 99% identical in the sequences of our protein coding genes to our sister species the Neanderthals ( Homo neanderthalensis ) [ 10 ]. The Neanderthals had large brains and were able to inhabit much of Eurasia from around 350,000 years ago. If the Neanderthals had language, that would place its origin at least as far back as the time of our common ancestor with them, currently thought to be around 550,000 to 750,000 years ago [ 10 , 11 ].

However, even as recently as 40,000 years ago in Europe, the Neanderthals show almost no evidence of the symbolic thinking—no art or sculpture for example—that we often associate with language, and little evidence of the cultural attainments of Homo sapiens of the same era. By 40,000 years ago, Homo sapiens had plentiful art, musical instruments and specialized tools such as sewing needles. Neanderthals probably didn’t even have sewn clothing, instead they would have merely draped themselves with skins [ 12 ]. And, despite evidence that around 1–5% of the human genome might be derived from human–Neanderthal matings [ 13 ], the Neanderthals went extinct as a species while we flourished.

Can genetic evidence help to decide when language evolved?

Yes. Modern humans and Neanderthals share a derived version of a transcription factor gene known as FOXP2 that differs from the chimpanzee version by two amino acid replacements [ 14 ]. FOXP2 influences the fine-motor control of facial muscles required for the production of speech. Indeed, inserting this derived form into mice causes them to squeak differently [ 15 ]! However, in spite of having identical primary sequences to Neanderthals, modern humans have acquired changes to the regulation of their FOXP2 genes that seem likely to cause their FOXP2 to be expressed differently to that of the Neanderthals [ 16 ], and these expression differences are pronounced in brain neurons. Combining these genetic hints with the differences in symbolic and cultural behaviour that are evident from the fossil record suggests language arose in our lineage sometime after our split from our common ancestor with Neanderthals, and probably by no later than 150,000 to 200,000 years ago.

Was there a single origin of language?

This question has parallels in biological evolution. Did life evolve once or many times? The presence of the same RNA and DNA in all organisms and homologies in the machinery of DNA transcription and translation suggest that at least all current life on Earth has a common origin. It is possible that life evolved more than once but all descendants of these other origins went extinct and left no fossil or other traces.

With language the inference is harder to make because features such as vocabulary and grammar change too rapidly to be able to link all of the world’s languages to a common original mother tongue. On the other hand, all human languages rely on combining sounds or ‘phones’ to make words, many of those sounds are common across languages, different languages seem to structure the world semantically in similar ways [ 17 ], all human languages recognize the past, present and future and all human languages structure words into sentences [ 18 ]. All humans are also capable of learning and speaking each other’s languages (some phones are unique to some language families—such as the famous ‘click’ sound of some San languages of Southern Africa—but these are probably within the capability of all human speakers if they are exposed to learning that sound at the right time of life).

These considerations suggest that the anatomical, neurological and physiological underpinnings of language are shared among all of humanity. If the capacity for language did evolve more than once, all traces of it seem to have been lost. This conclusion is buttressed by the FOXP2 evidence (all humans share the same derived gene) and by the fact that genetic data point to all modern humans descending from a common ancestor [ 19 ].

Is language evolution like biological evolution?

Darwin observed that “The formation of different languages and of distinct species, and the proofs that both have been developed through a gradual process, are curiously the same” (page 59 in [ 20 ]). He also asserted that “The survival and preservation of certain favoured words in the struggle for existence is natural selection.” (pages 59–60 in [ 20 ]).

Darwin was right on both counts. Linguists have known from at least the late 18th century [ 21 ]—about 100 years before Darwin—that languages predominantly evolve by a process of descent with modification from earlier ancestral languages, just as biological species descend from earlier ancestral forms. An example is differences observed between the ancient Greek vocabulary in Homer’s Iliad from around 750 BCE and modern Greek vocabulary (Table  1 ) [ 22 ]: some words have merely changed their pronunciation while others have been replaced by new unrelated words.

Regarding Darwin’s assertions that certain words are favoured in the ‘struggle for existence’, it is useful to remember that there is seldom any connection between a sound (a word) and its meaning. This means that selection is reasonably free to choose among words and so features of the words we actually use might reveal its actions. The simplest example is that words that are used more often—such as I , he , she , it , the , you —tend to be shorter, and consequently easier to pronounce, than less frequently used words, such as obstreperous or catafalque [ 23 ]. This is an example of a form of natural selection except here instead of biological individuals competing in the physical environment to survive and reproduce, words compete for space in the environment of the human mind. Our minds give preference to shorter versions of the frequently used words, presumably to reduce effort [ 23 ]. This pressure is relaxed among the less frequently used words, allowing them to be longer. It might also be the case that once the frequently used words have occupied the space of possible short words, there are fewer opportunities for the less frequently used words [ 24 ].

Is it possible to reconstruct the history of a group of languages like we do with species?

Yes. Using common lists of words that are found in all or nearly all languages, linguists can identify shared sets of cognate words—words that descend from common ancestral words— just as it is possible to identify homologous genes that share a common ancestral gene. For instance the Spanish mano (‘hand’) and the French main descend from the earlier Latin manus , while the English and German words hand do not. A cognate set identifies groups of related languages. In the example here mano and main identify the so-called Romance languages (Spanish, French, Italian, Portuguese) and hand and hand identify the Germanic languages (Fig.  1 ). By combining the information in many different cognate sets with appropriate statistical models [ 25 , 26 ], it is possible to infer detailed family histories or phylogenetic trees of language families, such as has been done for the Indo-European languages (Fig.  1 ). These phylogenies are directly analogous to phylogenies of biological species.

Phylogenetic tree of a small subset of the approximately 400 or so Indo-European languages. Words that the languages use for the meaning ‘hand’ are colour-coded to identify cognate classes. Rectangles along the branches identify regions of the tree where new cognate classes might have arisen. Here the French and Spanish languages share cognate forms for ‘hand’ derived from an earlier Latin form ‘manus’. French and Spanish are part of the familiar grouping of Romance languages. By comparison, the word ‘hand’ is cognate between English and German and this cognate class identifies part of the Germanic grouping of languages. The words for ‘hand’ in Greek and in the extinct Anatolian languages Hittite and Tocharian form two additional cognate sets. Combining many different cognate sets from many different vocabulary items allows investigators to draw detailed phylogenetic trees of entire language families (see text)

What other evolutionary features do genes and language share?

Linguistic and biological evolution share features beyond descent with modification and selection, including mechanisms of mutation and replication, speciation, drift and horizontal transfer (Table  2 ). At a deeper level, both genes and languages can be represented as digital systems of inheritance, built on the transmission of discrete chunks of information—genes in the case of biological organisms, and words in the case of language. Genes in turn comprise combinations of the four bases or nucleotides (A, C, G, T) while words can be modelled as comprising combinations of discrete sounds or phones (in fact, phones or sounds vary in a continuous space but languages are commonly represented as expressing a particular set of discrete phonemes).

These similarities mean that we can—and should—think of language as a system for the transmission of information that is tantamount to ‘aural DNA’. Even the peculiar phenomenon of concerted evolution in genetics—where a nucleotide replacement at a specific site in one gene is quickly followed by the same nucleotide replacement at the same site in other, typically related, genes—is also observed in language. Known as regular sound change , a specific phone or sound changes over a relatively short period of time to the same other phone in many words in the lexicon [ 27 , 28 ]. A well-known example is the p → f sound change in the Germanic languages where an older Indo-European p sound was replaced by an f sound, such as in pater → father ; or pes, pedis → foot .

Can changes to language be used to trace human history?

There are currently about 7000 languages spoken around the world, meaning that, oddly, most of us cannot communicate with most other members of our species! Even this number is probably down from the peak of human linguistic diversity that was likely to have occurred around 10,000 years ago, just prior to the invention of agriculture [ 29 ]. Before that time, all human groups had been hunter-gatherers, living in small mobile tribal societies. Farming societies were demographically more prosperous and group sizes were larger than among hunter-gatherers, so the expansion of agriculturalists likely replaced many smaller linguistic groups. Today, there are few hunter-gatherer societies left so our linguistic diversity reflects our relatively recent agricultural past.

Phylogenies of languages can be used in combination with geographical information or information on cultural practices to investigate questions of human history, such as the spread of agriculture. Phylogenies of language families have been used to study the timing, causes and geographic spread of groups of farmers/fishing populations, including the Indo-Europeans [ 30 , 31 , 32 , 33 ]; the pace of occupation of the Pacific by the Austronesian people [ 34 ]; and the migration routes of the Bantu-speaking people through Africa [ 35 , 36 ].

Linguistic phylogenies are also used to investigate questions of human cultural evolution, including the evolution and spread of dairying [ 37 , 38 , 39 ], relationships between religious and political practices [ 40 ], changing political structures [ 41 ] and the age of fairy tales [ 42 ], and have even supplied a date for Homer’s Iliad [ 22 ].

What role has language played in our species’ success?

Language has played a prominent and possibly pre-eminent role in our species’ history. Consider that where all other species tend to be found in the environments their genes adapt them to, humans can adapt at the cultural level, acquiring the knowledge and producing the tools, shelters, clothing and other artefacts necessary for survival in diverse habitats [ 12 , 43 ]. Thus, chimpanzees are found in the dense forests of Africa but not out on the savannah or in deserts or cold regions; camels are found in dry regions but not in forests or mountaintops, and so on for other species. Humans, on the other hand, despite being a species that probably evolved on the African savannahs, have been able to occupy nearly every habitat on Earth. Our behaviour is like that of a collection of biological species [ 43 ]. Why this striking difference?

It is probably down to language. Possessing language, humans have had a high-fidelity code for transmitting detailed information down the generations. Many, if not most, of the things we make use of in our everyday lives rely on specialized knowledge or skills to produce. The information behind these was historically coded in verbal instructions, and with the advent of writing it could be stored and become increasingly complex.

Possessing language, then, is behind humans’ ability to produce sophisticated cultural adaptations that have accumulated one on top of the other throughout our history as a species. Today as a result of this capability we live in a world full of technologies that few of us even understand. Because culture, riding on the back of language, can evolve more rapidly than genes, the relative genetic homogeneity of humanity in contrast to our cultural diversity shows that our ‘aural DNA’ has probably been more important in our short history than genes.

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Acknowledgements

An Advanced Investigator Award 268744 to M. Pagel from the European Research Council has supported most of my recent research on language evolution.

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Freedom of Speech

[ Editor’s Note: The following new entry by Jeffrey W. Howard replaces the former entry on this topic by the previous author. ]

Human beings have significant interests in communicating what they think to others, and in listening to what others have to say. These interests make it difficult to justify coercive restrictions on people’s communications, plausibly grounding a moral right to speak (and listen) to others that is properly protected by law. That there ought to be such legal protections for speech is uncontroversial among political and legal philosophers. But disagreement arises when we turn to the details. What are the interests or values that justify this presumption against restricting speech? And what, if anything, counts as an adequate justification for overcoming the presumption? This entry is chiefly concerned with exploring the philosophical literature on these questions.

The entry begins by distinguishing different ideas to which the term “freedom of speech” can refer. It then reviews the variety of concerns taken to justify freedom of speech. Next, the entry considers the proper limits of freedom of speech, cataloging different views on when and why restrictions on communication can be morally justified, and what considerations are relevant when evaluating restrictions. Finally, it considers the role of speech intermediaries in a philosophical analysis of freedom of speech, with special attention to internet platforms.

1. What is Freedom of Speech?

2.1 listener theories, 2.2 speaker theories, 2.3 democracy theories, 2.4 thinker theories, 2.5 toleration theories, 2.6 instrumental theories: political abuse and slippery slopes, 2.7 free speech skepticism, 3.1 absoluteness, coverage, and protection, 3.2 the limits of free speech: external constraints, 3.3 the limits of free speech: internal constraints, 3.4 proportionality: chilling effects and political abuse, 3.5 necessity: the counter-speech alternative, 4. the future of free speech theory: platform ethics, other internet resources, related entries.

In the philosophical literature, the terms “freedom of speech”, “free speech”, “freedom of expression”, and “freedom of communication” are mostly used equivalently. This entry will follow that convention, notwithstanding the fact that these formulations evoke subtly different phenomena. For example, it is widely understood that artistic expressions, such as dancing and painting, fall within the ambit of this freedom, even though they don’t straightforwardly seem to qualify as speech , which intuitively connotes some kind of linguistic utterance (see Tushnet, Chen, & Blocher 2017 for discussion). Still, they plainly qualify as communicative activity, conveying some kind of message, however vague or open to interpretation it may be.

Yet the extension of “free speech” is not fruitfully specified through conceptual analysis alone. The quest to distinguish speech from conduct, for the purpose of excluding the latter from protection, is notoriously thorny (Fish 1994: 106), despite some notable attempts (such as Greenawalt 1989: 58ff). As John Hart Ely writes concerning Vietnam War protesters who incinerated their draft cards, such activity is “100% action and 100% expression” (1975: 1495). It is only once we understand why we should care about free speech in the first place—the values it instantiates or serves—that we can evaluate whether a law banning the burning of draft cards (or whatever else) violates free speech. It is the task of a normative conception of free speech to offer an account of the values at stake, which in turn can illuminate the kinds of activities wherein those values are realized, and the kinds of restrictions that manifest hostility to those values. For example, if free speech is justified by the value of respecting citizens’ prerogative to hear many points of view and to make up their own minds, then banning the burning of draft cards to limit the views to which citizens will be exposed is manifestly incompatible with that purpose. If, in contrast, such activity is banned as part of a generally applied ordinance restricting fires in public, it would likely raise no free-speech concerns. (For a recent analysis of this issue, see Kramer 2021: 25ff).

Accordingly, the next section discusses different conceptions of free speech that arise in the philosophical literature, each oriented to some underlying moral or political value. Before turning to the discussion of those conceptions, some further preliminary distinctions will be useful.

First, we can distinguish between the morality of free speech and the law of free speech. In political philosophy, one standard approach is to theorize free speech as a requirement of morality, tracing the implications of such a theory for law and policy. Note that while this is the order of justification, it need not be the order of investigation; it is perfectly sensible to begin by studying an existing legal protection for speech (such as the First Amendment in the U.S.) and then asking what could justify such a protection (or something like it).

But of course morality and law can diverge. The most obvious way they can diverge is when the law is unjust. Existing legal protections for speech, embodied in the positive law of particular jurisdictions, may be misguided in various ways. In other words, a justified legal right to free speech, and the actual legal right to free speech in the positive law of a particular jurisdiction, can come apart. In some cases, positive legal rights might protect too little speech. For example, some jurisdictions’ speech laws make exceptions for blasphemy, such that criminalizing blasphemy does not breach the legal right to free speech within that legal system. But clearly one could argue that a justified legal right to free speech would not include any such exception. In other cases, positive legal rights might perhaps protect too much speech. Consider the fact that, as a matter of U.S. constitutional precedent, the First Amendment broadly protects speech that expresses or incites racial or religious hatred. Plainly we could agree that this is so as a matter of positive law while disagreeing about whether it ought to be so. (This is most straightforwardly true if we are legal positivists. These distinctions are muddied by moralistic theories of constitutional interpretation, which enjoin us to interpret positive legal rights in a constitutional text partly through the prism of our favorite normative political theory; see Dworkin 1996.)

Second, we can distinguish rights-based theories of free speech from non-rights-based theories. For many liberals, the legal right to free speech is justified by appealing to an underlying moral right to free speech, understood as a natural right held by all persons. (Some use the term human right equivalently—e.g., Alexander 2005—though the appropriate usage of that term is contested.) The operative notion of a moral right here is that of a claim-right (to invoke the influential analysis of Hohfeld 1917); it thereby correlates to moral duties held by others (paradigmatically, the state) to respect or protect the right. Such a right is natural in that it exerts normative force independently of whether anyone thinks it does, and regardless of whether it is codified into the law. A tyrannical state that imprisons dissidents acts unjustly, violating moral rights, even if there is no legal right to freedom of expression in its legal system.

For others, the underlying moral justification for free speech law need not come in the form of a natural moral right. For example, consequentialists might favor a legal right to free speech (on, e.g., welfare-maximizing grounds) without thinking that it tracks any underlying natural right. Or consider democratic theorists who have defended legal protections for free speech as central to democracy. Such theorists may think there is an underlying natural moral right to free speech, but they need not (especially if they hold an instrumental justification for democracy). Or consider deontologists who have argued that free speech functions as a kind of side-constraint on legitimate state action, requiring that the state always justify its decisions in a manner that respects citizens’ autonomy (Scanlon 1972). This theory does not cast free speech as a right, but rather as a principle that forbids the creation of laws that restrict speech on certain grounds. In the Hohfeldian analysis (Hohfeld 1917), such a principle may be understood as an immunity rather than a claim-right (Scanlon 2013: 402). Finally, some “minimalists” (to use a designation in Cohen 1993) favor legal protection for speech principally in response to government malice, corruption, and incompetence (see Schauer 1982; Epstein 1992; Leiter 2016). Such theorists need not recognize any fundamental moral right, either.

Third, among those who do ground free speech in a natural moral right, there is scope for disagreement about how tightly the law should mirror that right (as with any right; see Buchanan 2013). It is an open question what the precise legal codification of the moral right to free speech should involve. A justified legal right to freedom of speech may not mirror the precise contours of the natural moral right to freedom of speech. A raft of instrumental concerns enters the downstream analysis of what any justified legal right should look like; hence a defensible legal right to free speech may protect more speech (or indeed less speech) than the underlying moral right that justifies it. For example, even if the moral right to free speech does not protect so-called hate speech, such speech may still merit legal protection in the final analysis (say, because it would be too risky to entrust states with the power to limit those communications).

2. Justifying Free Speech

I will now examine several of the morally significant considerations taken to justify freedom of expression. Note that while many theorists have built whole conceptions of free speech out of a single interest or value alone, pluralism in this domain remains an option. It may well be that a plurality of interests serves to justify freedom of expression, properly understood (see, influentially, Emerson 1970 and Cohen 1993).

Suppose a state bans certain books on the grounds that it does not want us to hear the messages or arguments contained within them. Such censorship seems to involve some kind of insult or disrespect to citizens—treating us like children instead of adults who have a right to make up our own minds. This insight is fundamental in the free speech tradition. On this view, the state wrongs citizens by arrogating to itself the authority to decide what messages they ought to hear. That is so even if the state thinks that the speech will cause harm. As one author puts it,

the government may not suppress speech on the ground that the speech is likely to persuade people to do something that the government considers harmful. (Strauss 1991: 335)

Why are restrictions on persuasive speech objectionable? For some scholars, the relevant wrong here is a form of disrespect for citizens’ basic capacities (Dworkin 1996: 200; Nagel 2002: 44). For others, the wrong here inheres in a violation of the kind of relationship the state should have with its people: namely, that it should always act from a view of them as autonomous, and so entitled to make up their own minds (Scanlon 1972). It would simply be incompatible with a view of ourselves as autonomous—as authors of our own lives and choices—to grant the state the authority to pre-screen which opinions, arguments, and perspectives we should be allowed to think through, allowing us access only to those of which it approves.

This position is especially well-suited to justify some central doctrines of First Amendment jurisprudence. First, it justifies the claim that freedom of expression especially implicates the purposes with which the state acts. There are all sorts of legitimate reasons why the state might restrict speech (so-called “time, place, and manner” restrictions)—for example, noise curfews in residential neighborhoods, which do not raise serious free speech concerns. Yet when the state restricts speech with the purpose of manipulating the communicative environment and controlling the views to which citizens are exposed, free speech is directly affronted (Rubenfeld 2001; Alexander 2005; Kramer 2021). To be sure, purposes are not all that matter for free speech theory. For example, the chilling effects of otherwise justified speech regulations (discussed below) are seldom intended. But they undoubtedly matter.

Second, this view justifies the related doctrines of content neutrality and viewpoint neutrality (see G. Stone 1983 and 1987) . Content neutrality is violated when the state bans discussion of certain topics (“no discussion of abortion”), whereas viewpoint neutrality is violated when the state bans advocacy of certain views (“no pro-choice views may be expressed”). Both affront free speech, though viewpoint-discrimination is especially egregious and so even harder to justify. While listener autonomy theories are not the only theories that can ground these commitments, they are in a strong position to account for their plausibility. Note that while these doctrines are central to the American approach to free speech, they are less central to other states’ jurisprudence (see A. Stone 2017).

Third, this approach helps us see that free speech is potentially implicated whenever the state seeks to control our thoughts and the processes through which we form beliefs. Consider an attempt to ban Marx’s Capital . As Marx is deceased, he is probably not wronged through such censorship. But even if one held idiosyncratic views about posthumous rights, such that Marx were wronged, it would be curious to think this was the central objection to such censorship. Those with the gravest complaint would be the living adults who have the prerogative to read the book and make up their own minds about it. Indeed free speech may even be implicated if the state banned watching sunsets or playing video games on the grounds that is disapproved of the thoughts to which such experiences might give rise (Alexander 2005: 8–9; Kramer 2021: 22).

These arguments emphasize the noninstrumental imperative of respecting listener autonomy. But there is an instrumental version of the view. Our autonomy interests are not merely respected by free speech; they are promoted by an environment in which we learn what others have to say. Our interests in access to information is served by exposure to a wide range of viewpoints about both empirical and normative issues (Cohen 1993: 229), which help us reflect on what goals to choose and how best to pursue them. These informational interests are monumental. As Raz suggests, if we had to choose whether to express our own views on some question, or listen to the rest of humanity’s views on that question, we would choose the latter; it is our interest as listeners in the public good of a vibrant public discourse that, he thinks, centrally justifies free speech (1991).

Such an interest in acquiring justified beliefs, or in accessing truth, can be defended as part of a fully consequentialist political philosophy. J.S. Mill famously defends free speech instrumentally, appealing to its epistemic benefits in On Liberty . Mill believes that, given our fallibility, we should routinely keep an open mind as to whether a seemingly false view may actually be true, or at least contain some valuable grain of truth. And even where a proposition is manifestly false, there is value in allowing its expression so that we can better apprehend why we take it to be false (1859: chapter 2), enabled through discursive conflict (cf. Simpson 2021). Mill’s argument focuses especially on the benefits to audiences:

It is is not on the impassioned partisan, it is on the calmer and more disinterested bystander, that this collision of opinions works its salutary effect. (1859: chapter 2, p. 94)

These views are sometimes associated with the idea of a “marketplace of ideas”, whereby the open clash of views inevitably leads to the correct ones winning out in debate. Few in the contemporary literature holds such a strong teleological thesis about the consequences of unrestricted debate (e.g., see Brietzke 1997; cf. Volokh 2011). Much evidence from behavioral economics and social psychology, as well as insights about epistemic injustice from feminist epistemology, strongly suggest that human beings’ rational powers are seriously limited. Smug confidence in the marketplace of ideas belies this. Yet it is doubtful that Mill held such a strong teleological thesis (Gordon 1997). Mill’s point was not that unrestricted discussion necessarily leads people to acquire the truth. Rather, it is simply the best mechanism available for ascertaining the truth, relative to alternatives in which some arbiter declares what he sees as true and suppresses what he sees as false (see also Leiter 2016).

Note that Mill’s views on free speech in chapter 2 in On Liberty are not simply the application of the general liberty principle defended in chapter 1 of that work; his view is not that speech is anodyne and therefore seldom runs afoul of the harm principle. The reason a separate argument is necessary in chapter 2 is precisely that he is carving out a partial qualification of the harm principle for speech (on this issue see Jacobson 2000, Schauer 2011b, and Turner 2014). On Mill’s view, plenty of harmful speech should still be allowed. Imminently dangerous speech, where there is no time for discussion before harm eventuates, may be restricted; but where there is time for discussion, it must be allowed. Hence Mill’s famous example that vociferous criticism of corn dealers as

starvers of the poor…ought to be unmolested when simply circulated through the press, but may justly incur punishment when delivered orally to an excited mob assembled before the house of a corn dealer. (1859: chapter 3, p. 100)

The point is not that such speech is harmless; it’s that the instrumental benefits of permitting its expressions—and exposing its falsehood through public argument—justify the (remaining) costs.

Many authors have unsurprisingly argued that free speech is justified by our interests as speakers . This family of arguments emphasizes the role of speech in the development and exercise of our personal autonomy—our capacity to be the reflective authors of our own lives (Baker 1989; Redish 1982; Rawls 2005). Here an emphasis on freedom of expression is apt; we have an “expressive interest” (Cohen 1993: 224) in declaring our views—about the good life, about justice, about our identity, and about other aspects of the truth as we see it.

Our interests in self-expression may not always depend on the availability of a willing audience; we may have interests simply in shouting from the rooftops to declare who we are and what we believe, regardless of who else hears us. Hence communications to oneself—for example, in a diary or journal—are plausibly protected from interference (Redish 1992: 30–1; Shiffrin 2014: 83, 93; Kramer 2021: 23).

Yet we also have distinctive interests in sharing what we think with others. Part of how we develop our conceptions of the good life, forming judgments about how to live, is precisely through talking through the matter with others. This “deliberative interest” in directly served through opportunities to tell others what we think, so that we can learn from their feedback (Cohen 1993). Such encounters also offer opportunities to persuade others to adopt our views, and indeed to learn through such discussions who else already shares our views (Raz 1991).

Speech also seems like a central way in which we develop our capacities. This, too, is central to J.S. Mill’s defense of free speech, enabling people to explore different perspectives and points of view (1859). Hence it seems that when children engage in speech, to figure out what they think and to use their imagination to try out different ways of being in the world, they are directly engaging this interest. That explains the intuition that children, and not just adults, merit at least some protection under a principle of freedom of speech.

Note that while it is common to refer to speaker autonomy , we could simply refer to speakers’ capacities. Some political liberals hold that an emphasis on autonomy is objectionably Kantian or otherwise perfectionist, valorizing autonomy as a comprehensive moral ideal in a manner that is inappropriate for a liberal state (Cohen 1993: 229; Quong 2011). For such theorists, an undue emphasis on autonomy is incompatible with ideals of liberal neutrality toward different comprehensive conceptions of the good life (though cf. Shiffrin 2014: 81).

If free speech is justified by the importance of our interests in expressing ourselves, this justifies negative duties to refrain from interfering with speakers without adequate justification. Just as with listener theories, a strong presumption against content-based restrictions, and especially against viewpoint discrimination, is a clear requirement of the view. For the state to restrict citizens’ speech on the grounds that it disfavors what they have to say would affront the equal freedom of citizens. Imagine the state were to disallow the expression of Muslim or Jewish views, but allow the expression of Christian views. This would plainly transgress the right to freedom of expression, by valuing certain speakers’ interests in expressing themselves over others.

Many arguments for the right to free speech center on its special significance for democracy (Cohen 1993; Heinze 2016: Heyman 2009; Sunstein 1993; Weinstein 2011; Post 1991, 2009, 2011). It is possible to defend free speech on the noninstrumental ground that it is necessary to respect agents as democratic citizens. To restrict citizens’ speech is to disrespect their status as free and equal moral agents, who have a moral right to debate and decide the law for themselves (Rawls 2005).

Alternatively (or additionally), one can defend free speech on the instrumental ground that free speech promotes democracy, or whatever values democracy is meant to serve. So, for example, suppose the purpose of democracy is the republican one of establishing a state of non-domination between relationally egalitarian citizens; free speech can be defended as promoting that relation (Whitten 2022; Bonotti & Seglow 2022). Or suppose that democracy is valuable because of its role in promoting just outcomes (Arneson 2009) or tending to track those outcomes in a manner than is publicly justifiable (Estlund 2008) or is otherwise epistemically valuable (Landemore 2013).

Perhaps free speech doesn’t merely respect or promote democracy; another framing is that it is constitutive of it (Meiklejohn 1948, 1960; Heinze 2016). As Rawls says: “to restrict or suppress free political speech…always implies at least a partial suspension of democracy” (2005: 254). On this view, to be committed to democracy just is , in part, to be committed to free speech. Deliberative democrats famously contend that voting merely punctuates a larger process defined by a commitment to open deliberation among free and equal citizens (Gutmann & Thompson 2008). Such an unrestricted discussion is marked not by considerations of instrumental rationality and market forces, but rather, as Habermas puts it, “the unforced force of the better argument” (1992 [1996: 37]). One crucial way in which free speech might be constitutive of democracy is if it serves as a legitimation condition . On this view, without a process of open public discourse, the outcomes of the democratic decision-making process lack legitimacy (Dworkin 2009, Brettschneider 2012: 75–78, Cohen 1997, and Heinze 2016).

Those who justify free speech on democratic grounds may view this as a special application of a more general insight. For example, Scanlon’s listener theory (discussed above) contends that the state must always respect its citizens as capable of making up their own minds (1972)—a position with clear democratic implications. Likewise, Baker is adamant that both free speech and democracy are justified by the same underlying value of autonomy (2009). And while Rawls sees the democratic role of free speech as worthy of emphasis, he is clear that free speech is one of several basic liberties that enable the development and exercise of our moral powers: our capacities for a sense of justice and for the rational pursuit a lifeplan (2005). In this way, many theorists see the continuity between free speech and our broader interests as moral agents as a virtue, not a drawback (e.g., Kendrick 2017).

Even so, some democracy theorists hold that democracy has a special role in a theory of free speech, such that political speech in particular merits special protection (for an overview, see Barendt 2005: 154ff). One consequence of such views is that contributions to public discourse on political questions merit greater protection under the law (Sunstein 1993; cf. Cohen 1993: 227; Alexander 2005: 137–8). For some scholars, this may reflect instrumental anxieties about the special danger that the state will restrict the political speech of opponents and dissenters. But for others, an emphasis on political speech seems to reflect a normative claim that such speech is genuinely of greater significance, meriting greater protection, than other kinds of speech.

While conventional in the free speech literature, it is artificial to separate out our interests as speakers, listeners, and democratic citizens. Communication, and the thinking that feeds into it and that it enables, invariably engages our interests and activities across all these capacities. This insight is central to Seana Shiffrin’s groundbreaking thinker-based theory of freedom of speech, which seeks to unify the range of considerations that have informed the traditional theories (2014). Like other theories (e.g., Scanlon 1978, Cohen 1993), Shiffrin’s theory is pluralist in the range of interests it appeals to. But it offers a unifying framework that explains why this range of interests merits protection together.

On Shiffrin’s view, freedom of speech is best understood as encompassing both freedom of communication and freedom of thought, which while logically distinct are mutually reinforcing and interdependent (Shiffrin 2014: 79). Shiffrin’s account involves several profound claims about the relation between communication and thought. A central contention is that “free speech is essential to the development, functioning, and operation of thinkers” (2014: 91). This is, in part, because we must often externalize our ideas to articulate them precisely and hold them at a distance where we can evaluate them (p. 89). It is also because we work out what we think largely by talking it through with others. Such communicative processes may be monological, but they are typically dialogical; speaker and listener interests are thereby mutually engaged in an ongoing manner that cannot be neatly disentangled, as ideas are ping-ponged back and forth. Moreover, such discussions may concern democratic politics—engaging our interests as democratic citizens—but of course they need not. Aesthetics, music, local sports, the existence of God—these all are encompassed (2014: 92–93). Pace prevailing democratic theories,

One’s thoughts about political affairs are intrinsically and ex ante no more and no less central to the human self than thoughts about one’s mortality or one’s friends. (Shiffrin 2014: 93)

The other central aspect of Shiffrin’s view appeals to the necessity of communication for successfully exercising our moral agency. Sincere communication enables us

to share needs, emotions, intentions, convictions, ambitions, desires, fantasies, disappointments, and judgments. Thereby, we are enabled to form and execute complex cooperative plans, to understand one another, to appreciate and negotiate around our differences. (2014: 1)

Without clear and precise communication of the sort that only speech can provide, we cannot cooperate to discharge our collective obligations. Nor can we exercise our normative powers (such as consenting, waiving, or promising). Our moral agency thus depends upon protected channels through which we can relay our sincere thoughts to one another. The central role of free speech is to protect those channels, by ensuring agents are free to share what they are thinking without fear of sanction.

The thinker-based view has wide-ranging normative implications. For example, by emphasizing the continuity of speech and thought (a connection also noted in Macklem 2006 and Gilmore 2011), Shiffrin’s view powerfully explains the First Amendment doctrine that compelled speech also constitutes a violation of freedom of expression. Traditional listener- and speaker-focused theories seemingly cannot explain what is fundamentally objectionable with forcing someone to declare a commitment to something, as with children compelled to pledge allegiance to the American flag ( West Virginia State Board of Education v. Barnette 1943). “What seems most troubling about the compelled pledge”, Shiffrin writes,

is that the motive behind the regulation, and its possible effect, is to interfere with the autonomous thought processes of the compelled speaker. (2014: 94)

Further, Shiffrin’s view explains why a concern for free speech does not merely correlate to negative duties not to interfere with expression; it also supports positive responsibilities on the part of the state to educate citizens, encouraging and supporting their development and exercise as thinking beings (2014: 107).

Consider briefly one final family of free speech theories, which appeal to the role of toleration or self-restraint. On one argument, freedom of speech is important because it develops our character as liberal citizens, helping us tame our illiberal impulses. The underlying idea of Lee Bollinger’s view is that liberalism is difficult; we recurrently face temptation to punish those who hold contrary views. Freedom of speech helps us to practice the general ethos of toleration in a manner than fortifies our liberal convictions (1986). Deeply offensive speech, like pro-Nazi speech, is protected precisely because toleration in these enormously difficult cases promotes “a general social ethic” of toleration more generally (1986: 248), thereby restraining unjust exercises of state power overall. This consequentialist argument treats the protection of offensive speech not as a tricky borderline case, but as “integral to the central functions of the principle of free speech” (1986: 133). It is precisely because tolerating evil speech involves “extraordinary self-restraint” (1986: 10) that it works its salutary effects on society generally.

The idea of self-restraint arises, too, in Matthew Kramer’s recent defense of free speech. Like listener theories, Kramer’s strongly deontological theory condemns censorship aimed at protecting audiences from exposure to misguided views. At the core of his theory is the thesis that the state’s paramount moral responsibility is to furnish the social conditions that serve the development and maintenance of citizens’ self-respect and respect for others. The achievement of such an ethically resilient citizenry, on Kramer’s view, has the effect of neutering the harmfulness of countless harmful communications. “Securely in a position of ethical strength”, the state “can treat the wares of pornographers and the maunderings of bigots as execrable chirps that are to be endured with contempt” (Kramer 2021: 147). In contrast, in a society where the state has failed to do its duty of inculcating a robust liberal-egalitarian ethos, the communication of illiberal creeds may well pose a substantial threat. Yet for the state then to react by banning such speech is

overweening because with them the system’s officials take control of communications that should have been defused (through the system’s fulfillment of its moral obligations) without prohibitory or preventative impositions. (2021: 147)

(One might agree with Kramer that this is so, but diverge by arguing that the state—having failed in its initial duty—ought to take measures to prevent the harms that flow from that failure.)

These theories are striking in that they assume that a chief task of free speech theory is to explain why harmful speech ought to be protected. This is in contrast to those who think that the chief task of free speech theory is to explain our interests in communicating with others, treating the further issue of whether (wrongfully) harmful communications should be protected as an open question, with different reasonable answers available (Kendrick 2017). In this way, toleration theories—alongside a lot of philosophical work on free speech—seem designed to vindicate the demanding American legal position on free speech, one unshared by virtually all other liberal democracies.

One final family of arguments for free speech appeals to the danger of granting the state powers it may abuse. On this view, we protect free speech chiefly because if we didn’t, it would be far easier for the state to silence its political opponents and enact unjust policies. On this view, a state with censorial powers is likely to abuse them. As Richard Epstein notes, focusing on the American case,

the entire structure of federalism, divided government, and the system of checks and balances at the federal level shows that the theme of distrust has worked itself into the warp and woof of our constitutional structure.

“The protection of speech”, he writes, “…should be read in light of these political concerns” (Epstein 1992: 49).

This view is not merely a restatement of the democracy theory; it does not affirm free speech as an element of valuable self-governance. Nor does it reduce to the uncontroversial thought that citizens need freedom of speech to check the behavior of fallible government agents (Blasi 1977). One need not imagine human beings to be particularly sinister to insist (as democracy theorists do) that the decisions of those entrusted with great power be subject to public discussion and scrutiny. The argument under consideration here is more pessimistic about human nature. It is an argument about the slippery slope that we create even when enacting (otherwise justified) speech restrictions; we set an unacceptable precedent for future conduct by the state (see Schauer 1985). While this argument is theoretical, there is clearly historical evidence for it, as in the manifold cases in which bans on dangerous sedition were used to suppress legitimate war protest. (For a sweeping canonical study of the uses and abuses of speech regulations during wartime, with a focus on U.S. history, see G. Stone 2004.)

These instrumental concerns could potentially justify the legal protection for free speech. But they do not to attempt to justify why we should care about free speech as a positive moral ideal (Shiffrin 2014: 83n); they are, in Cohen’s helpful terminology, “minimalist” rather than “maximalist” (Cohen 1993: 210). Accordingly, they cannot explain why free speech is something that even the most trustworthy, morally competent administrations, with little risk of corruption or degeneration, ought to respect. Of course, minimalists will deny that accounting for speech’s positive value is a requirement of a theory of free speech, and that critiquing them for this omission begs the question.

Pluralists may see instrumental concerns as valuably supplementing or qualifying noninstrumental views. For example, instrumental concerns may play a role in justifying deviations between the moral right to free communication, on the one hand, and a properly specified legal right to free communication, on the other. Suppose that there is no moral right to engage in certain forms of harmful expression (such as hate speech), and that there is in fact a moral duty to refrain from such expression. Even so, it does not follow automatically that such a right ought to be legally enforced. Concerns about the dangers of granting the state such power plausibly militate against the enforcement of at least some of our communicative duties—at least in those jurisdictions that lack robust and competently administered liberal-democratic safeguards.

This entry has canvassed a range of views about what justifies freedom of expression, with particular attention to theories that conceive free speech as a natural moral right. Clearly, the proponents of such views believe that they succeed in this justificatory effort. But others dissent, doubting that the case for a bona fide moral right to free speech comes through. Let us briefly note the nature of this challenge from free speech skeptics , exploring a prominent line of reply.

The challenge from skeptics is generally understood as that of showing that free speech is a special right . As Leslie Kendrick notes,

the term “special right” generally requires that a special right be entirely distinct from other rights and activities and that it receive a very high degree of protection. (2017: 90)

(Note that this usage is not to be confused from the alternative usage of “special right”, referring to conditional rights arising out of particular relationships; see Hart 1955.)

Take each aspect in turn. First, to vindicate free speech as a special right, it must serve some distinctive value or interest (Schauer 2015). Suppose free speech were just an implication of a general principle not to interfere in people’s liberty without justification. As Joel Feinberg puts it, “Liberty should be the norm; coercion always needs some special justification” (1984: 9). In such a case, then while there still might be contingent, historical reasons to single speech out in law as worthy of protection (Alexander 2005: 186), such reasons would not track anything especially distinctive about speech as an underlying moral matter. Second, to count as a special right, free speech must be robust in what it protects, such that only a compelling justification can override it (Dworkin 2013: 131). This captures the conviction, prominent among American constitutional theorists, that “any robust free speech principle must protect at least some harmful speech despite the harm it may cause” (Schauer 2011b: 81; see also Schauer 1982).

If the task of justifying a moral right to free speech requires surmounting both hurdles, it is a tall order. Skeptics about a special right to free speech doubt that the order can be met, and so deny that a natural moral right to freedom of expression can be justified (Schauer 2015; Alexander & Horton 1983; Alexander 2005; Husak 1985). But these theorists may be demanding too much (Kendrick 2017). Start with the claim that free speech must be distinctive. We can accept that free speech be more than simply one implication of a general presumption of liberty. But need it be wholly distinctive? Consider the thesis that free speech is justified by our autonomy interests—interests that justify other rights such as freedom of religion and association. Is it a problem if free speech is justified by interests that are continuous with, or overlap with, interests that justify other rights? Pace the free speech skeptics, maybe not. So long as such claims deserve special recognition, and are worth distinguishing by name, this may be enough (Kendrick 2017: 101). Many of the views canvassed above share normative bases with other important rights. For example, Rawls is clear that he thinks all the basic liberties constitute

essential social conditions for the adequate development and full exercise of the two powers of moral personality over a complete life. (Rawls 2005: 293)

The debate, then, is whether such a shared basis is a theoretical virtue (or at least theoretically unproblematic) or whether it is a theoretical vice, as the skeptics avow.

As for the claim that free speech must be robust, protecting harmful speech, “it is not necessary for a free speech right to protect harmful speech in order for it to be called a free speech right” (Kendrick 2017: 102). We do not tend to think that religious liberty must protect harmful religious activities for it to count as a special right. So it would be strange to insist that the right to free speech must meet this burden to count as a special right. Most of the theorists mentioned above take themselves to be offering views that protect quite a lot of harmful speech. Yet we can question whether this feature is a necessary component of their views, or whether we could imagine variations without this result.

3. Justifying Speech Restrictions

When, and why, can restrictions on speech be justified? It is common in public debate on free speech to hear the provocative claim that free speech is absolute . But the plausibility of such a claim depends on what is exactly meant by it. If understood to mean that no communications between humans can ever be restricted, such a view is held by no one in the philosophical debate. When I threaten to kill you unless you hand me your money; when I offer to bribe the security guard to let me access the bank vault; when I disclose insider information that the company in which you’re heavily invested is about to go bust; when I defame you by falsely posting online that you’re a child abuser; when I endanger you by labeling a drug as safe despite its potentially fatal side-effects; when I reveal your whereabouts to assist a murderer intent on killing you—across all these cases, communications may be uncontroversially restricted. But there are different views as to why.

To help organize such views, consider a set of distinctions influentially defended by Schauer (from 1982 onward). The first category involves uncovered speech : speech that does not even presumptively fall within the scope of a principle of free expression. Many of the speech-acts just canvassed, such as the speech involved in making a threat or insider training, plausibly count as uncovered speech. As the U.S. Supreme Court has said of fighting words (e.g., insults calculated to provoke a street fight),

such utterances are no essential part of any exposition of ideas, and are of such slight social value as a step to truth that any benefit that may be derived from them is clearly outweighed by the social interest in order and morality. ( Chaplinsky v. New Hampshire 1942)

The general idea here is that some speech simply has negligible—and often no —value as free speech, in light of its utter disconnection from the values that justify free speech in the first place. (For discussion of so-called “low-value speech” in the U.S. context, see Sunstein 1989 and Lakier 2015.) Accordingly, when such low-value speech is harmful, it is particularly easy to justify its curtailment. Hence the Court’s view that “the prevention and punishment of [this speech] have never been thought to raise any Constitutional problem”. For legislation restricting such speech, the U.S. Supreme Court applies a “rational basis” test, which is very easy to meet, as it simply asks whether the law is rationally related to a legitimate state interest. (Note that it is widely held that it would still be impermissible to selectively ban low-value speech on a viewpoint-discriminatory basis—e.g., if a state only banned fighting words from left-wing activists while allowing them from right-wing activists.)

Schauer’s next category concerns speech that is covered but unprotected . This is speech that engages the values that underpin free speech; yet the countervailing harm of the speech justifies its restriction. In such cases, while there is real value in such expression as free speech, that value is outweighed by competing normative concerns (or even, as we will see below, on behalf of the very values that underpin free speech). In U.S. constitutional jurisprudence, this category encompasses those extremely rare cases in which restrictions on political speech pass the “strict scrutiny” test, whereby narrow restrictions on high-value speech can be justified due to the compelling state interests thereby served. Consider Holder v. Humanitarian Law Project 2010, in which the Court held that an NGO’s legal advice to a terrorist organization on how to pursue peaceful legal channels were legitimately criminalized under a counter-terrorism statute. While such speech had value as free speech (at least on one interpretation of this contested ruling), the imperative of counter-terrorism justified its restriction. (Arguably, commercial speech, while sometimes called low-value speech by scholars, falls into the covered but unprotected category. Under U.S. law, legislation restricting it receives “intermediate scrutiny” by courts—requiring restrictions to be narrowly drawn to advance a substantial government interest. Such a test suggests that commercial speech has bona fide free-speech value, making it harder to justify regulations on it than regulations on genuinely low-value speech like fighting words. It simply doesn’t have as much free-speech value as categories like political speech, religious speech, or press speech, all of which trigger the strict scrutiny test when restricted.)

As a philosophical matter, we can reasonably disagree about what speech qualifies as covered but unprotected (and need not treat the verdicts of the U.S. Supreme Court as philosophically decisive). For example, consider politically-inflected hate speech, which advances repugnant ideas about the inferior status of certain groups. One could concur that there is substantial free-speech value in such expression, just because it involves the sincere expression of views about central questions of politics and justice (however misguided the views doubtlessly are). Yet one could nevertheless hold that such speech should not be protected in virtue of the substantial harms to which it can lead. In such cases, the free-speech value is outweighed. Many scholars who defend the permissibility of legal restrictions on hate speech hold such a view (e.g., Parekh 2012; Waldron 2012). (More radically, one could hold that such speech’s value is corrupted by its evil, such that it qualifies as genuinely low-value; Howard 2019a.)

The final category of speech encompasses expression that is covered and protected . To declare that speech is protected just is to conclude that it is immune from restriction. A preponderance of human communications fall into this category. This does not mean that such speech can never be regulated ; content-neutral time, place, and manner regulations (e.g., prohibiting loud nighttime protests) can certainly be justified (G. Stone 1987). But such regulations must not be viewpoint discriminatory; they must apply even-handedly across all forms of protected speech.

Schauer’s taxonomy offers a useful organizing framework for how we should think about different forms of speech. Where does it leave the claim that free speech is absolute? The possibility of speech that is covered but unprotected suggests that free speech should sometimes be restricted on account of rival normative concerns. Of course, one could contend that such a category, while logically possible, is substantively an empty set; such a position would involve some kind of absoluteness about free speech (holding that where free-speech values are engaged by expression, no countervailing values can ever be weighty enough to override them). Such a position would be absolutist in a certain sense while granting the permissibility of restrictions on speech that do not engage the free-speech values. (For a recent critique of Schauer’s framework, arguing that governmental designation of some speech as low-value is incompatible with the very ideal of free speech, see Kramer 2021: 31.)

In what follows, this entry will focus on Schauer’s second category: speech that is covered by a free speech principle, but is nevertheless unprotected because of the harms it causes. How do we determine what speech falls into this category? How, in other words, do we determine the limits of free speech? Unsurprisingly, this is where most of the controversy lies.

Most legal systems that protect free speech recognize that the right has limits. Consider, for example, international human rights law, which emphatically protects the freedom of speech as a fundamental human right while also affirming specific restrictions on certain seriously harmful speech. Article 19 of the International Covenant of Civil and Political Rights declares that “[e]veryone shall have the right to freedom of expression; this right shall include freedom to seek, receive and impart information and ideas of all kinds”—but then immediately notes that this right “carries with it special duties and responsibilities”. The subsequent ICCPR article proceeds to endorse legal restrictions on “advocacy of national, racial or religious hatred that constitutes incitement to discrimination, hostility or violence”, as well as speech constituting “propaganda for war” (ICCPR). While such restrictions would plainly be struck down as unconstitutional affronts to free speech in the U.S., this more restrictive approach prevails in most liberal democracies’ treatment of harmful speech.

Set aside the legal issue for now. How should we think about how to determine the limits of the moral right free speech? Those seeking to justify limits on speech tend to appeal to one of two strategies (Howard and Simpson forthcoming). The first strategy appeals to the importance of balancing free speech against other moral values when they come into conflict. This strategy involves external limits on free speech. (The next strategy, discussed below, invokes free speech itself, or the values that justify it, as limit-setting rationales; it thus involves internal limits on free speech.)

A balancing approach recognizes a moral conflict between unfettered communication and external values. Consider again the case of hate speech, understood as expression that attacks members of socially vulnerable groups as inferior or dangerous. On all of the theories canvassed above, there are grounds for thinking that restrictions on hate speech are prima facie in violation of the moral right to free speech. Banning hate speech to prevent people from hearing ideas that might incline them to bigotry plainly seems to disrespect listener autonomy. Further, even when speakers are expressing prejudiced views, they are still engaging their autonomous faculties. Certainly, they are expressing views on questions of public political concern, even false ones. And as thinkers they are engaged in the communication of sincere testimony to others. On many of the leading theories, the values underpinning free speech seem to be militate against bans on hate speech.

Even so, other values matter. Consider, for example, the value of upholding the equal dignity of all citizens. A central insight of critical race theory is that public expressions of white supremacy, for example, attack and undermine that equal dignity (Matsuda, Lawrence, Delgado, & Crenshaw 1993). On Jeremy Waldron’s view (2012), hate speech is best understood as a form of group defamation, launching spurious attacks on others’ reputations and thereby undermining their standing as respected equals in their own community (relatedly, see Beauharnais v. Illinois 1952).

Countries that ban hate speech, accordingly, are plausibly understood not as opposed to free speech, but as recognizing the importance that it be balanced when conflicting with other values. Such balancing can be understood in different ways. In European human rights law, for example, the relevant idea is that the right to free speech is balanced against other rights ; the relevant task, accordingly, is to specify what counts as a proportionate balance between these rights (see Alexy 2003; J. Greene 2021).

For others, the very idea of balancing rights undermines their deontic character. This alternative framing holds that the balancing occurs before we specify what rights are; on this view, we balance interests against each other, and only once we’ve undertaken that balancing do we proceed to define what our rights protect. As Scanlon puts it,

The only balancing is balancing of interests. Rights are not balanced, but are defined, or redefined, in the light of the balance of interests and of empirical facts about how these interests can best be protected. (2008: 78)

This balancing need not come in the form of some crude consequentialism; otherwise it would be acceptable to limit the rights of the few to secure trivial benefits for the many. On a contractualist moral theory such as Scanlon’s, the test is to assess the strength of any given individual’s reason to engage in (or access) the speech, against the strength of any given individual’s reason to oppose it.

Note that those who engage in balancing need not give up on the idea of viewpoint neutrality; they can accept that, as a general principle, the state should not restrict speech on the grounds that it disapproves of its message and dislikes that others will hear it. The point, instead, is that this commitment is defeasible; it is possible to be overridden.

One final comment is apt. Those who are keen to balance free speech against other values tend to be motivated by the concern that speech can cause harm, either directly or indirectly (on this distinction, see Schauer 1993). But to justify restrictions on speech, it is not sufficient (and perhaps not even necessary) to show that such speech imposes or risks imposing harm. The crucial point is that the speech is wrongful (or, perhaps, wrongfully harmful or risky) , breaching a moral duty that speakers owe to others. Yet very few in the free speech literature think that the mere offensiveness of speech is sufficient to justify restrictions on it. Even Joel Feinberg, who thinks offensiveness can sometimes be grounds for restricting conduct, makes a sweeping exception for

[e]xpressions of opinion, especially about matters of public policy, but also about matters of empirical fact, and about historical, scientific, theological, philosophical, political, and moral questions. (1985: 44)

And in many cases, offensive speech may be actively salutary, as when racists are offended by defenses of racial equality (Waldron 1987). Accordingly, despite how large it looms in public debate, discussion of offensive speech will not play a major role in the discussion here.

We saw that one way to justify limits on free speech is to balance it against other values. On that approach, free speech is externally constrained. A second approach, in contrast, is internally constrained. On this approach, the very values that justify free speech themselves determine its own limits. This is a revisionist approach to free speech since, unlike orthodox thinking, it contends that a commitment to free speech values can counterintuitively support the restriction of speech—a surprising inversion of traditional thinking on the topic (see Howard and Simpson forthcoming). This move—justifying restrictions on speech by appealing to the values that underpin free speech—is now prevalent in the philosophical literature (for an overview, see Barendt 2005: 1ff).

Consider, for example, the claim that free speech is justified by concerns of listener autonomy. On such a view, as we saw above, autonomous citizens have interests in exposure to a wide range of viewpoints, so that they can decide for themselves what to believe. But many have pointed out that this is not autonomous citizens’ only interest; they also have interests in not getting murdered by those incited by incendiary speakers (Amdur 1980). Likewise, insofar as being targeted by hate speech undermines the exercise of one’s autonomous capacities, appeal to the underlying value of autonomy could well support restrictions on such speech (Brison 1998; see also Brink 2001). What’s more, if our interests as listeners in acquiring accurate information is undermined by fraudulent information, then restrictions on such information could well be compatible with our status as autonomous; this was one of the insights that led Scanlon to complicate his theory of free speech (1978).

Or consider the theory that free speech is justified because of its role in enabling autonomous speakers to express themselves. But as Japa Pallikkathayil has argued, some speech can intimidate its audiences into staying silent (as with some hate speech), out of fear for what will happen if they speak up (Pallikkathayil 2020). In principle, then, restrictions on hate speech may serve to support the value of speaker expression, rather than undermine it (see also Langton 2018; Maitra 2009; Maitra & McGowan 2007; and Matsuda 1989: 2337). Indeed, among the most prominent claims in feminist critiques of pornography is precisely that it silences women—not merely through its (perlocutionary) effects in inspiring rape, but more insidiously through its (illocutionary) effects in altering the force of the word “no” (see MacKinnon 1984; Langton 1993; and West 204 [2022]; McGowan 2003 and 2019; cf. Kramer 2021, pp. 160ff).

Now consider democracy theories. On the one hand, democracy theorists are adamant that citizens should be free to discuss any proposals, even the destruction of democracy itself (e.g., Meiklejohn 1948: 65–66). On the other hand, it isn’t obvious why citizens’ duties as democratic citizens could not set a limit to their democratic speech rights (Howard 2019a). The Nazi propagandist Goebbels is said to have remarked:

This will always remain one of the best jokes of democracy, that it gave its deadly enemies the means by which it was destroyed. (as quoted in Fox & Nolte 1995: 1)

But it is not clear why this is necessarily so. Why should we insist on a conception of democracy that contains a self-destruct mechanism? Merely stipulating that democracy requires this is not enough (see A. Greene and Simpson 2017).

Finally, consider Shiffrin’s thinker-based theory. Shiffrin’s view is especially well-placed to explain why varieties of harmful communications are protected speech; what the theory values is the sincere transmission of veridical testimony, whereby speakers disclose what they genuinely believe to others, even if what they believe is wrongheaded and dangerous. Yet because the sincere testimony of thinkers is what qualifies some communication for protection, Shiffrin is adamant that lying falls outside the protective ambit of freedom of expression (2014) This, then, sets an internal limit on her own theory (even if she herself disfavors all lies’ outright prohibition for reasons of tolerance). The claim that lying falls outside the protective ambit of free speech is itself a recurrent suggestion in the literature (Strauss 1991: 355; Brown 2023). In an era of rampant disinformation, this internal limit is of substantial practical significance.

Suppose the moral right (or principle) of free speech is limited, as most think, such that not all communications fall within its protective ambit (either for external reasons, internal reasons, or both). Even so, it does not follow that laws banning such unprotected speech can be justified all-things-considered. Further moral tests must be passed before any particular policy restricting speech can be justified. This sub-section focuses on the requirement that speech restrictions be proportionate .

The idea that laws implicating fundamental rights must be proportionate is central in many jurisdictions’ constitutional law, as well as in the international law of human rights. As a representative example, consider the specification of proportionality offered by the Supreme Court of Canada:

First, the measures adopted must be carefully designed to achieve the objective in question. They must not be arbitrary, unfair, or based on irrational considerations. In short, they must be rationally connected to the objective. Second, the means, even if rationally connected to the objective in this first sense, should impair “as little as possible” the right or freedom in question[…] Third, there must be a proportionality between the effects of the measures which are responsible for limiting the Charter right or freedom, and the objective which has been identified as of “sufficient importance” ( R v. Oakes 1986).

It is this third element (often called “proportionality stricto sensu ”) on which we will concentrate here; this is the focused sense of proportionality that roughly tracks how the term is used in the philosophical literatures on defensive harm and war, as well as (with some relevant differences) criminal punishment. (The strict scrutiny and intermediate scrutiny tests of U.S. constitutional law are arguably variations of the proportionality test; but set aside this complication for now as it distracts from the core philosophical issues. For relevant legal discussion, see Tsesis 2020.)

Proportionality, in the strict sense, concerns the relation between the costs or harms imposed by some measure and the benefits that the measure is designed to secure. The organizing distinction in recent philosophical literature (albeit largely missing in the literature on free speech) is one between narrow proportionality and wide proportionality . While there are different ways to cut up the terrain between these terms, let us stipulatively define them as follows. An interference is narrowly proportionate just in case the intended target of the interference is liable to bear the costs of that interference. An interference is widely proportionate just in case the collateral costs that the interference unintentionally imposes on others can be justified. (This distinction largely follows the literature in just war theory and the ethics of defensive force; see McMahan 2009.) While the distinction is historically absent from free speech theory, it has powerful payoffs in helping to structure this chaotic debate (as argued in Howard 2019a).

So start with the idea that restrictions on communication must be narrowly proportionate . For a restriction to be narrowly proportionate, those whose communications are restricted must be liable to bear their costs, such that they are not wronged by their imposition. One standard way to be liable to bear certain costs is to have a moral duty to bear them (Tadros 2012). So, for example, if speakers have a moral duty to refrain from libel, hate speech, or some other form of harmful speech, they are liable to bear at least some costs involved in the enforcement of that duty. Those costs cannot be unlimited; a policy of executing hate speakers could not plausibly be justified. Typically, in both defensive and punitive contexts, wrongdoers’ liability is determined by their culpability, the severity of their wrong, or some combination of the two. While it is difficult to say in the abstract what the precise maximal cost ceiling is for any given restriction, as it depends hugely on the details, the point is simply that there is some ceiling above which a speech restriction (like any restriction) imposes unacceptably high costs, even on wrongdoers.

Second, for a speech restriction to be justified, we must also show that it would be widely proportionate . Suppose a speaker is liable to bear the costs of some policy restricting her communication, such that she is not wronged by its imposition. It may be that the collateral costs of such a policy would render it unacceptable. One set of costs is chilling effects , the “overdeterrence of benign conduct that occurs incidentally to a law’s legitimate purpose or scope” (Kendrick 2013: 1649). The core idea is that laws targeting unprotected, legitimately proscribed expression may nevertheless end up having a deleterious impact on protected expression. This is because laws are often vague, overbroad, and in any case are likely to be misapplied by fallible officials (Schauer 1978: 699).

Note that if a speech restriction produces chilling effects, it does not follow that the restriction should not exist at all. Rather, concern about chilling effects instead suggests that speech restrictions should be under-inclusive—restricting less speech than is actually harmful—in order to create “breathing space”, or “a buffer zone of strategic protection” (Schauer 1978: 710) for legitimate expression and so reduce unwanted self-censorship. For example, some have argued that even though speech can cause harm recklessly or negligently, we should insist on specific intent as the mens rea of speech crimes in order to reduce any chilling effects that could follow (Alexander 1995: 21–128; Schauer 1978: 707; cf. Kendrick 2013).

But chilling effects are not the only sort of collateral effects to which speech restrictions could lead. Earlier we noted the risk that states might abuse their censorial powers. This, too, could militate in favor of underinclusive speech restrictions. Or the implication could be more radical. Consider the problem that it is difficult to author restrictions on hate speech in a tightly specified way; the language involved is open-ended in a manner that enables states to exercise considerable judgment in deciding what speech-acts, in fact, count as violations (see Strossen 2018). Given the danger that the state will misuse or abuse these laws to punish legitimate speech, some might think this renders their enactment widely disproportionate. Indeed, even if the law were well-crafted and would be judiciously applied by current officials, the point is that those in the future may not be so trustworthy.

Those inclined to accept such a position might simply draw the conclusion that legislatures ought to refrain from enacting laws against hate speech. A more radical conclusion is that the legal right to free speech ought to be specified so that hate speech is constitutionally protected. In other words, we ought to give speakers a legal right to violate their moral duties, since enforcing those moral duties through law is simply too risky. By appealing to this logic, it is conceivable that the First Amendment position on hate speech could be justified all-things-considered—not because the underlying moral right to free speech protects hate speech, but because hate speech must be protected for instrumental reasons of preventing future abuses of power (Howard 2019a).

Suppose certain restrictions on harmful speech can be justified as proportionate, in both the narrow and wide senses. This is still not sufficient to justify them all-things-considered. Additionally, they must be justified as necessary . (Note that some conceptions of proportionality in human rights law encompass the necessity requirement, but this entry follows the prevailing philosophical convention by treating them as distinct.)

Why might restrictions on harmful speech be unnecessary? One of the standard claims in the free speech literature is that we should respond to harmful speech not by banning it, but by arguing back against it. Counter-speech—not censorship—is the appropriate solution. This line of reasoning is old. As John Milton put it in 1644: “Let [Truth] and Falsehood grapple; who ever knew Truth put to the worse in a free and open encounter?” The insistence on counter-speech as the remedy for harmful speech is similarly found, as noted above, throughout chapter 2 of Mill’s On Liberty .

For many scholars, this line of reply is justified by the fact that they think the harmful speech in question is protected by the moral right to free speech. For such scholars, counter-speech is the right response because censorship is morally off the table. For other scholars, the recourse to counter-speech has a plausible distinct rationale (although it is seldom articulated): its possibility renders legal restrictions unnecessary. And because it is objectionable to use gratuitous coercion, legal restrictions are therefore impermissible (Howard 2019a). Such a view could plausibly justify Mill’s aforementioned analysis in the corn dealer example, whereby censorship is permissible but only when there’s no time for counter-speech—a view that is also endorsed by the U.S. Supreme Court in Brandenburg v. Ohio 395 U.S. 444 (1969).

Whether this argument succeeds depends upon a wide range of further assumptions—about the comparable effectiveness of counter-speech relative to law; about the burdens that counter-speech imposes on prospective counter-speakers. Supposing that the argument succeeds, it invites a range of further normative questions about the ethics of counter-speech. For example, it is important who has the duty to engage in counter-speech, who its intended audience is, and what specific forms the counter-speech ought to take—especially in order to maximize its persuasive effectiveness (Brettschneider 2012; Cepollaro, Lepoutre, & Simpson 2023; Howard 2021b; Lepoutre 2021; Badano & Nuti 2017). It is also important to ask questions about the moral limits of counter-speech. For example, insofar as publicly shaming wrongful speakers has become a prominent form of counter-speech, it is crucial to interrogate its permissibility (e.g., Billingham and Parr 2020).

This final section canvasses the young philosophical debate concerning freedom of speech on the internet. With some important exceptions (e.g., Barendt 2005: 451ff), this issue has only recently accelerated (for an excellent edited collection, see Brison & Gelber 2019). There are many normative questions to be asked about the moral rights and obligations of internet platforms. Here are three. First, do internet platforms have moral duties to respect the free speech of their users? Second, do internet platforms have moral duties to restrict (or at least refrain from amplifying) harmful speech posted by their users? And finally, if platforms do indeed have moral duties to restrict harmful speech, should those duties be legally enforced?

The reference to internet platforms , is a deliberate focus on large-scale social media platforms, through which people can discover and publicly share user-generated content. We set aside other entities such as search engines (Whitney & Simpson 2019), important though they are. That is simply because the central political controversies, on which philosophical input is most urgent, concern the large social-media platforms.

Consider the question of whether internet platforms have moral duties to respect the free speech of their users. One dominant view in the public discourse holds that the answer is no . On this view, platforms are private entities, and as such enjoy the prerogative to host whatever speech they like. This would arguably be a function of them having free speech rights themselves. Just as the free speech rights of the New York Times give it the authority to publish whatever op-eds it sees fit, the free speech rights of platforms give them the authority to exercise editorial or curatorial judgment about what speech to allow. On this view, if Facebook were to decide to become a Buddhist forum, amplifying the speech of Buddhist users and promoting Buddhist perspectives and ideas, and banning speech promoting other religions, it would be entirely within its moral (and thus proper legal) rights to do so. So, too, if it were to decide to become an atheist forum.

A radical alternative view holds that internet platforms constitute a public forum , a term of art from U.S. free speech jurisprudence used to designate spaces “designed for and dedicated to expressive activities” ( Southeastern Promotions Ltd., v. Conrad 1975). As Kramer has argued:

social-media platforms such as Facebook and Twitter and YouTube have become public fora. Although the companies that create and run those platforms are not morally obligated to sustain them in existence at all, the role of controlling a public forum morally obligates each such company to comply with the principle of freedom of expression while performing that role. No constraints that deviate from the kinds of neutrality required under that principle are morally legitimate. (Kramer 2021: 58–59)

On this demanding view, platforms’ duties to respect speech are (roughly) identical to the duties of states. Accordingly, if efforts by the state to restrict hate speech, pornography, and public health misinformation (for example) are objectionable affronts to free speech, so too are platforms’ content moderation rules for such content. A more moderate view does not hold that platforms are public forums as such, but holds that government channels or pages qualify as public forums (the claim at issue in Knight First Amendment Institute v. Trump (2019).)

Even if we deny that platforms constitute public forums, it is plausible that they engage in a governance function of some kind (Klonick 2018). As Jack Balkin has argued, the traditional model of free speech, which sees it as a relation between speakers and the state, is today plausibly supplanted by a triadic model, involving a more complex relation between speakers, governments, and intermediaries (2004, 2009, 2018, 2021). If platforms do indeed have some kind of governance function, it may well trigger responsibilities for transparency and accountability (as with new legislation such as the EU’s Digital Services Act and the UK’s Online Safety Act).

Second, consider the question of whether platforms have a duty to remove harmful content posted by users. Even those who regard them as public forums could agree that platforms may have a moral responsibility to remove illegal unprotected speech. Yet a dominant view in the public debate has historically defended platforms’ place as mere conduits for others’ speech. This is the current position under U.S. law (as with 47 U.S. Code §230), which broadly exempts platforms from liability for much illegal speech, such as defamation. On this view, we should view platforms as akin to bulletin boards: blame whoever posts wrongful content, but don’t hold the owner of the board responsible.

This view is under strain. Even under current U.S. law, platforms are liable for removing some content, such as child sexual abuse material and copyright infringements, suggesting that it is appropriate to demand some accountability for the wrongful content posted by others. An increasing body of philosophical work explores the idea that platforms are indeed morally responsible for removing extreme content. For example, some have argued that platforms have a special responsibility to prevent the radicalization that occurs on their networks, given the ways in which extreme content is amplified to susceptible users (Barnes 2022). Without engaging in moderation (i.e., removal) of harmful content, platforms are plausibly complicit with the wrongful harms perpetrated by users (Howard forthcoming).

Yet it remains an open question what a responsible content moderation policy ought to involve. Many are tempted by a juridical model, whereby platforms remove speech in accordance with clearly announced rules, with user appeals mechanisms in place for individual speech decisions to ensure they are correctly made (critiqued in Douek 2022b). Yet platforms have billions of users and remove millions of pieces of content per week. Accordingly, perfection is not possible. Moving quickly to remove harmful content during a crisis—e.g., Covid misinformation—will inevitably increase the number of false positives (i.e., legitimate speech taken down as collateral damage). It is plausible that the individualistic model of speech decisions adopted by courts is decidedly implausible to help us govern online content moderation; as noted in Douek 2021 and 2022a, what is needed is analysis of how the overall system should operate at scale, with a focus on achieving proportionality between benefits and costs. Alternatively, one might double down and insist that the juridical model is appropriate, given the normative significance of speech. And if it is infeasible for social-media companies to meet its demands given their size, then all the worse for social-media companies. On this view, it is they who must bend to meet the moral demands of free speech theory, not the other way around.

Substantial philosophical work needs to be done to deliver on this goal. The work is complicated by the fact that artificial intelligence (AI) is central to the processes of content moderation; human moderators, themselves subjected to terrible working conditions at long hours, work in conjunction with machine learning tools to identify and remove content that platforms have restricted. Yet AI systems notoriously are as biased as their training data. Further, their “black box” decisions are cryptic and cannot be easily understood. Given that countless speech decisions will necessarily be made without human involvement, it is right to ask whether it is reasonable to expect users to accept the deliverances of machines (e.g., see Vredenburgh 2022; Lazar forthcoming a). Note that machine intelligence is used not merely for content moderation, narrowly understood as the enforcement of rules about what speech is allowed. It is also deployed for the broader practice of content curation, determining what speech gets amplified — raising the question of what normative principles should govern such amplification; see Lazar forthcoming b).

Finally, there is the question of legal enforcement. Showing that platforms have the moral responsibility to engage in content moderation is necessary to justifying its codification into a legal responsibility. Yet it is not sufficient; one could accept that platforms have moral duties to moderate (some) harmful speech while also denying that those moral duties ought to be legally enforced. A strong, noninstrumental version of such a view would hold that while speakers have moral duties to refrain from wrongful speech, and platforms have duties not to platform or amplify it, the coercive enforcement of such duties would violate the moral right to freedom of expression. A more contingent, instrumental version of the view would hold that legal enforcement is not in principle impermissible; but in practice, it is simply too risky to grant the state the authority to enforce platforms’ and speakers’ moral duties, given the potential for abuse and overreach.

Liberals who champion the orthodox interpretation of the First Amendment, yet insist on robust content moderation, likely hold one or both of these views. Yet globally such views seem to be in the minority. Serious legislation is imminent that will subject social-media companies to burdensome regulation, in the form of such laws as the Digital Services Act in the European Union and the Online Safety Bill in the UK. Normatively evaluating such legislation is a pressing task. So, too, is the task of designing normative theories to guide the design of content moderation systems, and the wider governance of the digital public sphere. On both fronts, political philosophers should get back to work.

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• International Covenant on Civil and Political Rights (ICCPR) , adopted: 16 December 1966; Entry into force: 23 March 1976.
• Free Speech Debate
• Knight First Amendment Institute at Columbia University
• van Mill, David, “Freedom of Speech”, Stanford Encyclopedia of Philosophy (Winter 2023 Edition), Edward N. Zalta & Uri Nodelman (eds.), URL = < https://plato.stanford.edu/archives/win2023/entries/freedom-speech/ >. [This was the previous entry on this topic in the Stanford Encyclopedia of Philosophy – see the version history .]

ethics: search engines and | hate speech | legal rights | liberalism | Mill, John Stuart | Mill, John Stuart: moral and political philosophy | pornography: and censorship | rights | social networking and ethics | toleration

Acknowledgments

I am grateful to the editors and anonymous referees of this Encyclopedia for helpful feedback. I am greatly indebted to Robert Mark Simpson for many incisive suggestions, which substantially improved the entry. This entry was written while on a fellowship funded by UK Research & Innovation (grant reference MR/V025600/1); I am thankful to UKRI for the support.

Copyright © 2024 by Jeffrey W. Howard < jeffrey . howard @ ucl . ac . uk >

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Middle English humain , from Anglo-French, from Latin humanus ; akin to Latin homo human being — more at homage

15th century, in the meaning defined at sense 2

1509, in the meaning defined above

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Speech recognition, also known as automatic speech recognition (ASR), computer speech recognition or speech-to-text, is a capability that enables a program to process human speech into a written format.

While speech recognition is commonly confused with voice recognition, speech recognition focuses on the translation of speech from a verbal format to a text one whereas voice recognition just seeks to identify an individual user’s voice.

IBM has had a prominent role within speech recognition since its inception, releasing of “Shoebox” in 1962. This machine had the ability to recognize 16 different words, advancing the initial work from Bell Labs from the 1950s. However, IBM didn’t stop there, but continued to innovate over the years, launching VoiceType Simply Speaking application in 1996. This speech recognition software had a 42,000-word vocabulary, supported English and Spanish, and included a spelling dictionary of 100,000 words.

While speech technology had a limited vocabulary in the early days, it is utilized in a wide number of industries today, such as automotive, technology, and healthcare. Its adoption has only continued to accelerate in recent years due to advancements in deep learning and big data.  Research  (link resides outside ibm.com) shows that this market is expected to be worth USD 24.9 billion by 2025.

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Many speech recognition applications and devices are available, but the more advanced solutions use AI and machine learning . They integrate grammar, syntax, structure, and composition of audio and voice signals to understand and process human speech. Ideally, they learn as they go — evolving responses with each interaction.

The best kind of systems also allow organizations to customize and adapt the technology to their specific requirements — everything from language and nuances of speech to brand recognition. For example:

• Language weighting: Improve precision by weighting specific words that are spoken frequently (such as product names or industry jargon), beyond terms already in the base vocabulary.
• Speaker labeling: Output a transcription that cites or tags each speaker’s contributions to a multi-participant conversation.
• Acoustics training: Attend to the acoustical side of the business. Train the system to adapt to an acoustic environment (like the ambient noise in a call center) and speaker styles (like voice pitch, volume and pace).
• Profanity filtering: Use filters to identify certain words or phrases and sanitize speech output.

Meanwhile, speech recognition continues to advance. Companies, like IBM, are making inroads in several areas, the better to improve human and machine interaction.

The vagaries of human speech have made development challenging. It’s considered to be one of the most complex areas of computer science – involving linguistics, mathematics and statistics. Speech recognizers are made up of a few components, such as the speech input, feature extraction, feature vectors, a decoder, and a word output. The decoder leverages acoustic models, a pronunciation dictionary, and language models to determine the appropriate output.

Speech recognition technology is evaluated on its accuracy rate, i.e. word error rate (WER), and speed. A number of factors can impact word error rate, such as pronunciation, accent, pitch, volume, and background noise. Reaching human parity – meaning an error rate on par with that of two humans speaking – has long been the goal of speech recognition systems. Research from Lippmann (link resides outside ibm.com) estimates the word error rate to be around 4 percent, but it’s been difficult to replicate the results from this paper.

Various algorithms and computation techniques are used to recognize speech into text and improve the accuracy of transcription. Below are brief explanations of some of the most commonly used methods:

• Natural language processing (NLP): While NLP isn’t necessarily a specific algorithm used in speech recognition, it is the area of artificial intelligence which focuses on the interaction between humans and machines through language through speech and text. Many mobile devices incorporate speech recognition into their systems to conduct voice search—e.g. Siri—or provide more accessibility around texting. 
• Hidden markov models (HMM): Hidden Markov Models build on the Markov chain model, which stipulates that the probability of a given state hinges on the current state, not its prior states. While a Markov chain model is useful for observable events, such as text inputs, hidden markov models allow us to incorporate hidden events, such as part-of-speech tags, into a probabilistic model. They are utilized as sequence models within speech recognition, assigning labels to each unit—i.e. words, syllables, sentences, etc.—in the sequence. These labels create a mapping with the provided input, allowing it to determine the most appropriate label sequence.
• N-grams: This is the simplest type of language model (LM), which assigns probabilities to sentences or phrases. An N-gram is sequence of N-words. For example, “order the pizza” is a trigram or 3-gram and “please order the pizza” is a 4-gram. Grammar and the probability of certain word sequences are used to improve recognition and accuracy.
• Neural networks: Primarily leveraged for deep learning algorithms, neural networks process training data by mimicking the interconnectivity of the human brain through layers of nodes. Each node is made up of inputs, weights, a bias (or threshold) and an output. If that output value exceeds a given threshold, it “fires” or activates the node, passing data to the next layer in the network. Neural networks learn this mapping function through supervised learning, adjusting based on the loss function through the process of gradient descent.  While neural networks tend to be more accurate and can accept more data, this comes at a performance efficiency cost as they tend to be slower to train compared to traditional language models.
• Speaker Diarization (SD): Speaker diarization algorithms identify and segment speech by speaker identity. This helps programs better distinguish individuals in a conversation and is frequently applied at call centers distinguishing customers and sales agents.

A wide number of industries are utilizing different applications of speech technology today, helping businesses and consumers save time and even lives. Some examples include:

Automotive: Speech recognizers improves driver safety by enabling voice-activated navigation systems and search capabilities in car radios.

Technology: Virtual agents are increasingly becoming integrated within our daily lives, particularly on our mobile devices. We use voice commands to access them through our smartphones, such as through Google Assistant or Apple’s Siri, for tasks, such as voice search, or through our speakers, via Amazon’s Alexa or Microsoft’s Cortana, to play music. They’ll only continue to integrate into the everyday products that we use, fueling the “Internet of Things” movement.

Healthcare: Doctors and nurses leverage dictation applications to capture and log patient diagnoses and treatment notes.

Sales: Speech recognition technology has a couple of applications in sales. It can help a call center transcribe thousands of phone calls between customers and agents to identify common call patterns and issues. AI chatbots can also talk to people via a webpage, answering common queries and solving basic requests without needing to wait for a contact center agent to be available. It both instances speech recognition systems help reduce time to resolution for consumer issues.

Security: As technology integrates into our daily lives, security protocols are an increasing priority. Voice-based authentication adds a viable level of security.

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• Amnesty International UK / Issues

What is freedom of speech?

'Freedom of speech is the right to seek, receive and impart information and ideas of all kinds, by any means.'

Is freedom of speech a human right?

In the UK, Article 10 of the 1998 Human Rights Act protects our right to freedom of expression:

Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority and regardless of frontiers.

Are freedom of speech and freedom of expression the same thing? In the UK, freedom of speech is legally one part of the wider concept of freedom of expression.

Does freedom of speech have limits?

...and when it can't.

ANTI-PROTEST LAWS IN THE UK

Protest is not only a human right. It is a powerful way to change the world ✊🏽 People in power, afraid of change & afraid to be held accountable, want us to think that coming together to protect our rights doesn’t work. 🧵 5 protests that show #PeoplePower can win human rights — Amnesty UK (@AmnestyUK) August 23, 2023

Checks and balances

National security and public order.

RIGHT TO PROTEST IN THE UK

Rights and reputations of others

Media and journalists, whistleblowers, rights and responsibilities.

FREE COURSE

• Use your voice to stand up for human rights
• Learn more about protest rights in the UK
• Join our FREE course on freedom of expression
• Help us protect our right to protest in the UK

While you’re here…

Like you, we are horrified by the violence and the civilian death toll in Gaza, Israel and the rest of the Occupied Palestinian Territories. We’re calling for an immediate ceasefire by all parties in the occupied Gaza Strip and Israel to prevent further loss of civilian lives. Amnesty International is investigating mass summary killings, indiscriminate and disproportionate attacks, hostage-taking, and siege tactics.

As ever, our mission to protect human rights remains. Please donate today to help expose war crimes and protect human rights. Thank you.

Machine listening: Making speech recognition systems more inclusive

Study explores how african american english speakers adapt their speech to be understood by voice technology..

Interactions with voice technology, such as Amazon's Alexa, Apple's Siri, and Google Assistant, can make life easier by increasing efficiency and productivity. However, errors in generating and understanding speech during interactions are common. When using these devices, speakers often style-shift their speech from their normal patterns into a louder and slower register, called technology-directed speech.

Research on technology-directed speech typically focuses on mainstream varieties of U.S. English without considering speaker groups that are more consistently misunderstood by technology. In JASA Express Letters, published on behalf of the Acoustical Society of America by AIP Publishing, researchers from Google Research, the University of California, Davis, and Stanford University wanted to address this gap.

One group commonly misunderstood by voice technology are individuals who speak African American English, or AAE. Since the rate of automatic speech recognition errors can be higher for AAE speakers, downstream effects of linguistic discrimination in technology may result.

"Across all automatic speech recognition systems, four out of every ten words spoken by Black men were being transcribed incorrectly," said co-author Zion Mengesha. "This affects fairness for African American English speakers in every institution using voice technology, including health care and employment."

"We saw an opportunity to better understand this problem by talking to Black users and understanding their emotional, behavioral, and linguistic responses when engaging with voice technology," said co-author Courtney Heldreth.

The team designed an experiment to test how AAE speakers adapt their speech when imagining talking to a voice assistant, compared to talking to a friend, family member, or stranger. The study tested familiar human, unfamiliar human, and voice assistant-directed speech conditions by comparing speech rate and pitch variation. Study participants included 19 adults identifying as Black or African American who had experienced issues with voice technology. Each participant asked a series of questions to a voice assistant. The same questions were repeated as if speaking to a familiar person and, again, to a stranger. Each question was recorded for a total of 153 recordings.

Analysis of the recordings showed that the speakers exhibited two consistent adjustments when they were talking to voice technology compared to talking to another person: a slower rate of speech with less pitch variation (more monotone speech).

"These findings suggest that people have mental models of how to talk to technology," said co-author Michelle Cohn. "A set 'mode' that they engage to be better understood, in light of disparities in speech recognition systems."

There are other groups misunderstood by voice technology, such as second-language speakers. The researchers hope to expand the language varieties explored in human-computer interaction experiments and address barriers in technology so that it can support everyone who wants to use it.

• Communications
• Artificial Intelligence
• Information Technology
• Computer Science
• STEM Education
• Racial Disparity
• Media and Entertainment
• Voice over IP
• Speech recognition
• Consumerism
• Civil libertarianism
• Communication
• Social inequality
• Virtual reality

Story Source:

Materials provided by American Institute of Physics . Note: Content may be edited for style and length.

Journal Reference :

• Michelle Cohn, Zion Mengesha, Michal Lahav, Courtney Heldreth. African American English speakers’ pitch variation and rate adjustments for imagined technological and human addressees . JASA Express Letters , 2024; 4 (4) DOI: 10.1121/10.0025484

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Crackdown on Free Speech: ‘Extremism’ Redefinition Unites Campaigners in Condemnation of UK Government

Posted: 1 May 2024 | Last updated: 1 May 2024

Veteran activists and human rights campaigners have united in condemnation as the UK government faces backlash over its plans to broaden the definition of extremism. The move has sparked concerns about the erosion of civil liberties and the stifling of dissent. Here’s the full story.

Broaden Extremism Definition

The UK government is facing significant pushback from various quarters over its proposed plans to broaden the definition of extremism significantly.

Veteran Activists

The move, spearheaded by Michael Gove, the Communities Secretary, has drawn criticism from veteran activists across the entire political spectrum.

The redefinition aims to grant authorities the power to sever ties with groups deemed “extremist” for their purported undermining of British institutions or values.

Large-Scale Crackdown

However, many critics argue that such a broad definition could stifle dissent and the few remaining legitimate forms of activism following the government’s large-scale crackdown on protests in the last year.

Spanning the Gamut

Prominent figures in activism, spanning the gamut of causes from LGBTQ+ rights to more traditionally conservative causes like hunting, have expressed dismay over the government’s intentions.

“An Appalling Direction”

Labour peer Peter Hain, renowned for his anti-apartheid activism, condemned the proposed legislation, stating, “I think it’s an appalling direction to go down and it could probably have been applied to the suffragettes in their day, who were equally vilified, spat at, hated and treated very badly by the police and the authorities.”

Boycott Apartheid

Hain, a Labour peer who led a campaign in the 1970s to boycott the all-white South African rugby tour of the UK in protest of the nation’s apartheid regime, drew parallels with the historic struggles he and others faced.

“Hated and Attacked”

Hain stated, “At that time people like me and others involved were hated and attacked and vilified, and it’s only more recently that those who thought that way have come to understand why we needed to do what we did. But we would have been targeted under this new approach to a definition of extremism.”

Equal Opportunity Annoyance

The dissent isn’t confined to any particular ideological camp. Even conservative groups, like the Countryside Alliance, have voiced reservations.

“An Excuse to Crack Down”

Tim Bonner, the chief executive of the Countryside Alliance, told the Guardian, “We are concerned that defining extremism as something as woolly as ‘undermining fundamental British values’ will become an excuse to crack down on any opinion which isn’t shared by a majority of the population.”

“What Are British Values?”

Notably, human rights campaigners have also joined the chorus of criticism. Peter Tatchell, a stalwart defender of LGBTQ+ rights, stated, “The Tories seem to be suggesting that groups undermining ‘British values’ should be declared extremist and subject to new restrictions. But what are British values?”

“Slavery, Colonialism Homophobic Discrimination”

He continued, “They used to be slavery, colonialism, homophobic discrimination and the denial of votes to women and working-class people. British values are still contentious today.”

Criminalizing Protest

Tatchell went on to highlight the danger of criminalizing peaceful protests and suggested that activist actions he had taken in the past, such as his interrupting of Tony Blair in protest of the Iraq war, would, under the proposed legislation, be described as “extremist.”

Tachell is not alone in his concerns over the erosion of civil liberties, which resonate broadly throughout civil society.

Stringent Anti-Protest Laws

Tatchell also pointed out that the UK already possesses stringent anti-protest laws and argued that the proposed crackdown mirrors authoritarian regimes such as Putin’s Russia.

Secular Apprehensions

The National Secular Society (NSS) has also voiced apprehensions about the implications of the redefined extremism criteria.

Unfair Targeting

Stephen Evans, the NSS chief executive, warned that such expansive definitions could unfairly target secularists critical of religious institutions like the Church of England and the monarchy.

National Security

While the government frames its actions as necessary for safeguarding national security and preserving British values, critics contend that the proposed measures threaten the fundamental freedoms that British values encapsulate.

Mounting Pressure

Despite these reassurances, the government is facing mounting pressure to ensure that any new policies uphold the rights and liberties that are vital to a functioning democracy.

Severe Concerns

The controversy surrounding the UK government’s plans to redefine extremism reflects severe concerns about the erosion of civil liberties and the stifling of dissent.

Rallying the Troops

As the government faces becoming ever more unpopular and looks with dread upon the upcoming election, their recent moves to broaden the range of extremism seem, at best, a thinly veiled attempt to shore up die-hard conservative voters, who often stand in opposition to the vast majority of protest movements of the present day.

However, with even conservative organizations suggesting that the proposed legislation has gone too far, the government may have overplayed its hand. Only time will tell.

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Stranded: 15 Worst British Cars in History

Ever had a car that spent more time with the mechanic than on the road? A car that turned every journey into a game of “Will we actually get there?” If so, you might just see a familiar face (or should we say, chassis) in our countdown to the most unreliable British car in history. Stranded: 15 Worst British Cars in History

“Britain Will Become Unrecognizable” – Suella Braverman Spells Disaster for UK Amid Steep Rise in Visas Issued

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Step into the time machine and set the dial to the 1970s, a decade of disco, bell-bottoms, and some rather questionable choices. While the ’70s gave us iconic music and groundbreaking TV, not everything from this groovy era would get a green light today. 20 Things From the ‘70s That Are Not OK Today

20 Best and Worst Universities in the UK

Navigating the UK university landscape is like deciphering a complex code of rankings, reviews, and reputations to uncover where you’ll not just learn, but truly flourish. Whether you’re drawn to the historic halls of Oxford or the creative buzz of Goldsmiths, finding your perfect fit is about aligning your aspirations with the unique offerings of each institution. 20 Best and Worst Universities in the UK

The post Crackdown on Free Speech: ‘Extremism’ Redefinition Unites Campaigners in Condemnation  first appeared on  Edge Media .

Featured Image Credit: Shutterstock / Lomb.

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