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Speech is a human vocal
communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqui ...
using
language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...
. Each language uses
phonetic Phonetics is a branch of linguistics that studies how humans produce and perceive sounds, or in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. ...
combinations of
vowel A vowel is a syllabic speech sound pronounced without any stricture in the vocal tract. Vowels are one of the two principal classes of speech sounds, the other being the consonant. Vowels vary in quality, in loudness and also in quantity (leng ...
and
consonant In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are and pronounced with the lips; and pronounced with the front of the tongue; and pronounced wi ...
sounds that form the sound of its words (that is, all English words sound different from all French words, even if they are the same word, e.g., "role" or "hotel"), and using those words in their semantic character as words in the lexicon of a language according to the syntactic constraints that govern lexical words' function in a sentence. In speaking, speakers perform many different intentional speech acts, e.g., informing, declaring, asking, persuading, directing, and can use
enunciation Elocution is the study of formal speaking in pronunciation, grammar, style, and tone as well as the idea and practice of effective speech and its forms. It stems from the idea that while communication is symbolic, sounds are final and compelli ...
, intonation, degrees of
loudness In acoustics, loudness is the subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The relation of ph ...
,
tempo In musical terminology, tempo ( Italian, 'time'; plural ''tempos'', or ''tempi'' from the Italian plural) is the speed or pace of a given piece. In classical music, tempo is typically indicated with an instruction at the start of a piece (ofte ...
, and other non-representational or
paralinguistic Paralanguage, also known as vocalics, is a component of meta-communication that may modify meaning, give nuanced meaning, or convey emotion, by using techniques such as prosody, pitch, volume, intonation, etc. It is sometimes defined as relatin ...
aspects of vocalization to convey meaning. In their speech, speakers also unintentionally communicate many aspects of their social position such as sex, age, place of origin (through accent), physical states (alertness and sleepiness, vigor or weakness, health or illness), psychological states (emotions or moods), physico-psychological states (sobriety or
drunkenness Alcohol intoxication, also known as alcohol poisoning, commonly described as drunkenness or inebriation, is the negative behavior and physical effects caused by a recent consumption of alcohol. In addition to the toxicity of ethanol, the main ...
, normal consciousness and
trance Trance is a state of semi-consciousness in which a person is not self-aware and is either altogether unresponsive to external stimuli (but nevertheless capable of pursuing and realizing an aim) or is selectively responsive in following the dir ...
states), education or experience, and the like. Although people ordinarily use speech in dealing with other persons (or animals), when people swear they do not always mean to communicate anything to anyone, and sometimes in expressing urgent emotions or desires they use speech as a quasi-magical cause, as when they encourage a player in a game to do or warn them not to do something. There are also many situations in which people engage in solitary speech. People talk to themselves sometimes in acts that are a development of what some psychologists (e.g.,
Lev Vygotsky Lev Semyonovich Vygotsky (russian: Лев Семёнович Выго́тский, p=vɨˈɡotskʲɪj; be, Леў Сямёнавіч Выго́цкі, p=vɨˈɡotskʲɪj; – June 11, 1934) was a Soviet psychologist, known for his work on ps ...
) have maintained is the use of silent speech in an
interior monologue In literary criticism, stream of consciousness is a narrative mode or method that attempts "to depict the multitudinous thoughts and feelings which pass through the mind" of a narrator. The term was coined by Daniel Oliver in 1840 in ''First Li ...
to vivify and organize cognition, sometimes in the momentary adoption of a dual persona as self addressing self as though addressing another person. Solo speech can be used to memorize or to test one's memorization of things, and in
prayer Prayer is an invocation or act that seeks to activate a rapport with an object of worship through deliberate communication. In the narrow sense, the term refers to an act of supplication or intercession directed towards a deity or a deified ...
or in
meditation Meditation is a practice in which an individual uses a technique – such as mindfulness, or focusing the mind on a particular object, thought, or activity – to train attention and awareness, and achieve a mentally clear and emotionally calm ...
(e.g., the use of a
mantra A mantra ( Pali: ''manta'') or mantram (मन्त्रम्) is a sacred utterance, a numinous sound, a syllable, word or phonemes, or group of words in Sanskrit, Pali and other languages believed by practitioners to have religious, ...
). Researchers study many different aspects of speech: speech production and speech perception of the
sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' b ...
s used in a language, speech repetition,
speech error A speech error, commonly referred to as a slip of the tongue (Latin: , or occasionally self-demonstratingly, ) or misspeaking, is a deviation (conscious or unconscious) from the apparently intended form of an utterance.Bussmann, Hadumod. Routled ...
s, the ability to map heard spoken words onto the vocalizations needed to recreate them, which plays a key role in children's enlargement of their
vocabulary A vocabulary is a set of familiar words within a person's language. A vocabulary, usually developed with age, serves as a useful and fundamental tool for communication and acquiring knowledge. Acquiring an extensive vocabulary is one of the la ...
, and what different areas of the
human brain The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the act ...
, such as
Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production. Language processing has been linked to Broca's area since Pierr ...
and
Wernicke's area Wernicke's area (; ), also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to B ...
, underlie speech. Speech is the subject of study for
linguistics Linguistics is the science, scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, objective, and precise analysis of all aspects of language, particularly its nature and structure ...
, cognitive science, communication studies,
psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...
,
computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includi ...
,
speech pathology Speech is a human vocal communication using language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which hum ...
,
otolaryngology Otorhinolaryngology ( , abbreviated ORL and also known as otolaryngology, otolaryngology–head and neck surgery (ORL–H&N or OHNS), or ear, nose, and throat (ENT)) is a surgical subspeciality within medicine that deals with the surgical a ...
, and acoustics. Speech compares with
written language A written language is the representation of a spoken or gestural language by means of a writing system. Written language is an invention in that it must be taught to children, who will pick up spoken language or sign language by exposure eve ...
, which may differ in its vocabulary, syntax, and phonetics from the spoken language, a situation called
diglossia In linguistics, diglossia () is a situation in which two dialects or languages are used (in fairly strict compartmentalization) by a single language community. In addition to the community's everyday or vernacular language variety (labeled ...
. The evolutionary origins of speech are unknown and subject to much debate and speculation. While animals also communicate using vocalizations, and trained apes such as Washoe and
Kanzi Kanzi (born October 28, 1980), also known by the lexigram (from the character 太), is a male bonobo who has been the subject of several studies on great ape language. According to Sue Savage-Rumbaugh, a primatologist who has studied ...
can use simple
sign language Sign languages (also known as signed languages) are languages that use the visual-manual modality to convey meaning, instead of spoken words. Sign languages are expressed through manual articulation in combination with non-manual markers. Sign l ...
, no animals' vocalizations are articulated phonemically and syntactically, and do not constitute speech.


Evolution

Although related to the more general problem of the origin of language, the
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
of distinctively human speech capacities has become a distinct and in many ways separate area of scientific research. The topic is a separate one because language is not necessarily spoken: it can equally be
written Writing is a medium of human communication which involves the representation of a language through a system of physically inscribed, mechanically transferred, or digitally represented symbols. Writing systems do not themselves constitute h ...
or signed. Speech is in this sense optional, although it is the default modality for language. Monkeys, non-human apes and humans, like many other animals, have evolved specialised mechanisms for producing ''sound'' for purposes of social communication. On the other hand, no monkey or ape uses its ''tongue'' for such purposes. The human species' unprecedented use of the tongue, lips and other moveable parts seems to place speech in a quite separate category, making its evolutionary emergence an intriguing theoretical challenge in the eyes of many scholars. Determining the timeline of human speech evolution is made additionally challenging by the lack of data in the fossil record. The human
vocal tract The vocal tract is the cavity in human bodies and in animals where the sound produced at the sound source ( larynx in mammals; syrinx in birds) is filtered. In birds it consists of the trachea, the syrinx, the oral cavity, the upper part of th ...
does not fossilize, and indirect evidence of vocal tract changes in hominid fossils has proven inconclusive.


Production

Speech production is an unconscious multi-step process by which thoughts are generated into spoken utterances. Production involves the unconscious mind selecting appropriate words and the appropriate form of those words from the lexicon and morphology, and the organization of those words through the syntax. Then, the phonetic properties of the words are retrieved and the sentence is articulated through the articulations associated with those phonetic properties. In
linguistics Linguistics is the science, scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, objective, and precise analysis of all aspects of language, particularly its nature and structure ...
,
articulatory phonetics The field of articulatory phonetics is a subfield of phonetics that studies articulation and ways that humans produce speech. Articulatory phoneticians explain how humans produce speech sounds via the interaction of different physiological stru ...
is the study of how the tongue, lips, jaw, vocal cords, and other speech organs are used to make sounds. Speech sounds are categorized by manner of articulation and
place of articulation In articulatory phonetics, the place of articulation (also point of articulation) of a consonant is a location along the vocal tract where its production occurs. It is a point where a constriction is made between an active and a passive articula ...
. Place of articulation refers to where in the neck or mouth the airstream is constricted. Manner of articulation refers to the manner in which the speech organs interact, such as how closely the air is restricted, what form of airstream is used (e.g. pulmonic, implosive, ejectives, and clicks), whether or not the vocal cords are vibrating, and whether the nasal cavity is opened to the airstream. The concept is primarily used for the production of
consonant In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are and pronounced with the lips; and pronounced with the front of the tongue; and pronounced wi ...
s, but can be used for
vowels A vowel is a syllabic speech sound pronounced without any stricture in the vocal tract. Vowels are one of the two principal classes of speech sounds, the other being the consonant. Vowels vary in quality, in loudness and also in quantity (len ...
in qualities such as voicing and
nasalization In phonetics, nasalization (or nasalisation) is the production of a sound while the velum is lowered, so that some air escapes through the nose during the production of the sound by the mouth. An archetypal nasal sound is . In the Internation ...
. For any place of articulation, there may be several manners of articulation, and therefore several homorganic consonants. Normal human speech is pulmonic, produced with pressure from the lungs, which creates phonation in the glottis in the larynx, which is then modified by the vocal tract and mouth into different vowels and consonants. However humans can pronounce words without the use of the lungs and glottis in
alaryngeal speech Alaryngeal speech is speech using an airstream mechanism that uses features other than the glottis to create voicing. There are three types: esophageal, buccal, and pharyngeal speech. Each of these uses an alternative method of creating phonati ...
, of which there are three types:
esophageal speech Esophageal speech, also known as esophageal voice, is an airstream mechanism for speech that involves oscillation of the esophagus. This contrasts with traditional laryngeal speech, which involves oscillation of the vocal folds. In esophageal sp ...
, pharyngeal speech and buccal speech (better known as
Donald Duck talk Donald Duck talk, formally called buccal speech, is an alaryngeal form of vocalization which uses the inner cheek to produce sound rather than the larynx. also published as The speech is most closely associated with the Disney cartoon character, ...
).


Errors

Speech production is a complex activity, and as a consequence errors are common, especially in children. Speech errors come in many forms and are used to provide evidence to support hypotheses about the nature of speech. As a result, speech errors are often used in the construction of models for language production and
child language acquisition Language acquisition is the process by which humans acquire the capacity to perceive and comprehend language (in other words, gain the ability to be aware of language and to understand it), as well as to produce and use words and sentences to ...
. For example, the fact that children often make the error of over-regularizing the -ed past tense suffix in English (e.g. saying 'singed' instead of 'sang') shows that the regular forms are acquired earlier. Speech errors associated with certain kinds of aphasia have been used to map certain components of speech onto the brain and see the relation between different aspects of production; for example, the difficulty of
expressive aphasia Expressive aphasia, also known as Broca's aphasia, is a type of aphasia characterized by partial loss of the ability to produce language ( spoken, manual, or written), although comprehension generally remains intact. A person with expressive apha ...
patients in producing regular past-tense verbs, but not irregulars like 'sing-sang' has been used to demonstrate that regular inflected forms of a word are not individually stored in the lexicon, but produced from affixation to the base form.


Perception

Speech perception refers to the processes by which humans can interpret and understand the sounds used in language. The study of speech perception is closely linked to the fields of
phonetics Phonetics is a branch of linguistics that studies how humans produce and perceive sounds, or in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. ...
and
phonology Phonology is the branch of linguistics that studies how languages or dialects systematically organize their sounds or, for sign languages, their constituent parts of signs. The term can also refer specifically to the sound or sign system of a ...
in linguistics and cognitive psychology and perception in psychology. Research in speech perception seeks to understand how listeners recognize speech sounds and use this information to understand
spoken language A spoken language is a language produced by articulate sounds or (depending on one's definition) manual gestures, as opposed to a written language. An oral language or vocal language is a language produced with the vocal tract in contrast with a si ...
. Research into speech perception also has applications in building computer systems that can recognize speech, as well as improving speech recognition for hearing- and language-impaired listeners. Speech perception is categorical, in that people put the sounds they hear into categories rather than perceiving them as a spectrum. People are more likely to be able to hear differences in sounds across categorical boundaries than within them. A good example of this is
voice onset time In phonetics, voice onset time (VOT) is a feature of the production of stop consonants. It is defined as the length of time that passes between the release of a stop consonant and the onset of voicing, the vibration of the vocal folds, or, accor ...
(VOT), one aspect of the phonetic production of consonant sounds. For example, Hebrew speakers, who distinguish voiced /b/ from voiceless /p/, will more easily detect a change in VOT from -10 ( perceived as /b/ ) to 0 ( perceived as /p/ ) than a change in VOT from +10 to +20, or -10 to -20, despite this being an equally large change on the VOT spectrum.


Development

Most human children develop proto-speech babbling behaviors when they are four to six months old. Most will begin saying their first words at some point during the first year of life. Typical children progress through two or three word phrases before they are three to short sentences by four years of age.


Repetition

In speech repetition, speech being heard is quickly turned from sensory input into motor instructions needed for its immediate or delayed vocal imitation (in phonological memory). This type of mapping plays a key role in enabling children to expand their spoken vocabulary. Masur (1995) found that how often children repeat novel words versus those they already have in their lexicon is related to the size of their lexicon later on, with young children who repeat more novel words having a larger lexicon later in development. Speech repetition could help facilitate the acquisition of this larger lexicon.


Problems

There are several organic and psychological factors that can affect speech. Among these are: # Diseases and disorders of the lungs or the
vocal cords In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speec ...
, including paralysis, respiratory infections (bronchitis), vocal fold nodules and
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
s of the lungs and throat. # Diseases and disorders of the
brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
, including alogia,
aphasia Aphasia is an inability to comprehend or formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine but aphasia due to stroke is estimated to be 0.1–0.4% in t ...
s,
dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...
, dystonia and
speech processing Speech processing is the study of speech signals and the processing methods of signals. The signals are usually processed in a digital representation, so speech processing can be regarded as a special case of digital signal processing, applied t ...
disorders, where impaired motor planning, nerve transmission, phonological processing or perception of the message (as opposed to the actual sound) leads to poor speech production. # Hearing problems, such as
otitis media with effusion Otitis media is a group of inflammatory diseases of the middle ear. One of the two main types is acute otitis media (AOM), an infection of rapid onset that usually presents with ear pain. In young children this may result in pulling at the ear, ...
, and listening problems,
auditory processing disorder Auditory processing disorder (APD), rarely known as King-Kopetzky syndrome or auditory disability with normal hearing (ADN), is a neurodevelopmental disorder affecting the way the brain processes auditory information. Individuals with APD usually ...
s, can lead to phonological problems. In addition to
dysphasia Aphasia is an inability to comprehend or formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine but aphasia due to stroke is estimated to be 0.1–0.4% in th ...
, anomia and auditory processing disorder impede the quality of auditory perception, and therefore, expression. Those who are
deaf Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is written ...
or hard of hearing may be considered to fall into this category. # Articulatory problems, such as slurred speech, stuttering, lisping,
cleft palate A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The ...
,
ataxia Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...
, or nerve damage leading to problems in articulation.
Tourette syndrome Tourette syndrome or Tourette's syndrome (abbreviated as TS or Tourette's) is a common neurodevelopmental disorder that begins in childhood or adolescence. It is characterized by multiple movement (motor) tics and at least one vocal (phonic) ...
and
tic A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups.American Psychiatric Association (2000)DSM-IV-TR: Tourette's Disorder.''Diagnostic and Statistical Manual of Mental Disorders'', 4th ed., ...
s can also affect speech. Various congenital and acquired tongue diseases can affect speech as can
motor neuron disease Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...
. #
Psychiatric Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry. Initial psy ...
disorders have been shown to change speech acoustic features, where for instance,
fundamental frequency The fundamental frequency, often referred to simply as the ''fundamental'', is defined as the lowest frequency of a periodic waveform. In music, the fundamental is the musical pitch of a note that is perceived as the lowest partial present. I ...
of voice (perceived as pitch) tends to be significantly lower in
major depressive disorder Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Intro ...
than in healthy controls. Therefore, speech is being investigated as a potential biomarker for mental health disorders. Speech and language disorders can also result from stroke, brain injury, hearing loss, developmental delay, a cleft palate, cerebral palsy, or emotional issues.


Treatment

Speech-related diseases, disorders, and conditions can be treated by a speech-language pathologist (SLP) or speech therapist. SLPs assess levels of speech needs, make diagnoses based on the assessments, and then treat the diagnoses or address the needs.


Brain physiology


Classical model

The classical or Wernicke-Geschwind model of the language system in the brain focuses on
Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production. Language processing has been linked to Broca's area since Pierr ...
in the inferior
prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46 ...
, and
Wernicke's area Wernicke's area (; ), also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to B ...
in the posterior superior temporal gyrus on the
dominant hemisphere The lateralization of brain function is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. The median longitudinal fissure separates the human brain into two distinct cerebra ...
of the brain (typically the left hemisphere for language). In this model, a linguistic auditory signal is first sent from the
auditory cortex The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to ...
to Wernicke's area. The lexicon is accessed in Wernicke's area, and these words are sent via the
arcuate fasciculus The arcuate fasciculus (AF) is a bundle of axons that generally connects the Broca's area and the Wernicke's area in the brain. It is an association fiber tract connecting caudal temporal cortex and inferior frontal lobe. ''Fasciculus arcuatus'' i ...
to Broca's area, where morphology, syntax, and instructions for articulation are generated. This is then sent from Broca's area to the
motor cortex The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...
for articulation.
Paul Broca Pierre Paul Broca (, also , , ; 28 June 1824 – 9 July 1880) was a French physician, anatomist and anthropologist. He is best known for his research on Broca's area, a region of the frontal lobe that is named after him. Broca's area is involve ...
identified an approximate region of the brain in 1861 which, when damaged in two of his patients, caused severe deficits in speech production, where his patients were unable to speak beyond a few monosyllabic words. This deficit, known as Broca's or
expressive aphasia Expressive aphasia, also known as Broca's aphasia, is a type of aphasia characterized by partial loss of the ability to produce language ( spoken, manual, or written), although comprehension generally remains intact. A person with expressive apha ...
, is characterized by difficulty in speech production where speech is slow and labored, function words are absent, and syntax is severely impaired, as in telegraphic speech. In expressive aphasia, speech comprehension is generally less affected except in the comprehension of grammatically complex sentences.Hillis, A.E., & Caramazza, A. (2005). "Aphasia". In L. Nadel, ''Encyclopedia of cognitive science''. Hoboken, NJ: Wiley. Wernicke's area is named after
Carl Wernicke Carl (or Karl) Wernicke (; ; 15 May 1848 – 15 June 1905) was a German physician, anatomist, psychiatrist and neuropathologist. He is known for his influential research into the pathological effects of specific forms of encephalopathy and also ...
, who in 1874 proposed a connection between damage to the posterior area of the left superior temporal gyrus and aphasia, as he noted that not all aphasic patients had had damage to the prefrontal cortex. Damage to Wernicke's area produces Wernicke's or
receptive aphasia Wernicke's aphasia, also known as receptive aphasia, sensory aphasia or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent ...
, which is characterized by relatively normal syntax and prosody but severe impairment in lexical access, resulting in poor comprehension and nonsensical or jargon speech.


Modern research

Modern models of the neurological systems behind linguistic comprehension and production recognize the importance of Broca's and Wernicke's areas, but are not limited to them nor solely to the left hemisphere. Instead, multiple streams are involved in speech production and comprehension. Damage to the left
lateral sulcus In neuroanatomy, the lateral sulcus (also called Sylvian fissure, after Franciscus Sylvius, or lateral fissure) is one of the most prominent features of the human brain. The lateral sulcus is a deep fissure in each hemisphere that separates the ...
has been connected with difficulty in processing and producing morphology and syntax, while lexical access and comprehension of irregular forms (e.g. eat-ate) remain unaffected. Moreover, the circuits involved in human speech comprehension dynamically adapt with learning, for example, by becoming more efficient in terms of processing time when listening to familiar messages such as learned verses.


Animal communication

Some non-human animals can produce sounds or gestures resembling those of a human language. Several species or groups of animals have developed forms of communication which superficially resemble verbal language, however, these usually are not considered a language because they lack one or more of the defining characteristics, e.g.
grammar In linguistics, the grammar of a natural language is its set of structural constraints on speakers' or writers' composition of clauses, phrases, and words. The term can also refer to the study of such constraints, a field that includes domain ...
, syntax,
recursion Recursion (adjective: ''recursive'') occurs when a thing is defined in terms of itself or of its type. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in mathemati ...
, and displacement. Researchers have been successful in teaching some animals to make gestures similar to
sign language Sign languages (also known as signed languages) are languages that use the visual-manual modality to convey meaning, instead of spoken words. Sign languages are expressed through manual articulation in combination with non-manual markers. Sign l ...
, although whether this should be considered a language has been disputed.


See also

*
FOXP2 Forkhead box protein P2 (FOXP2) is a protein that, in humans, is encoded by the ''FOXP2'' gene. FOXP2 is a member of the forkhead box family of transcription factors, proteins that regulate gene expression by binding to DNA. It is expressed ...
* Freedom of speech * Imagined speech * Index of linguistics articles *
List of language disorders The following is a list of language disorders. A language disorder is a condition defined as a condition that limits or altogether stops natural speech Speech is a human vocal communication using language. Each language uses phonetic combina ...
* Spatial hearing loss *
Speechwriter A speechwriter is a person who is hired to prepare and write speeches that will be delivered by another person. Speechwriters are employed by many senior-level elected officials and executives in the government and private sectors. They can also b ...
*
Talking bird Talking birds are birds that can mimic the speech of humans. There is debate within the scientific community over whether some talking parrots also have some cognitive understanding of the language. Birds have varying degrees of talking ability: ...
s * Vocology * Public speaking


References


Further reading

* Fitzpatrick, Élizabeth M. ''Apprendre à écouter et à parler''. University of Ottawa Press, 2013
Available at
Project MUSE Project MUSE, a non-profit collaboration between libraries and publishers, is an online database of peer-reviewed academic journals and electronic books. Project MUSE contains digital humanities and social science content from over 250 univers ...
.


External links


Speaking captured by real-time MRI
YouTube YouTube is a global online video sharing and social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the second mo ...
{{Nonverbal communication Language Articles containing video clips