250px, copy with their own mouths">Children copy with their own mouths the words spoken by the mouths of those around them. That enables them to learn the pronunciation of words not already in their vocabulary.
Speech repetition occurs when individuals speech, speak the sounds that they have heard another person Speech production, pronounce or say. In other words, it is the saying by one individual of the spoken vocalizations made by another individual. Speech repetition requires the person repeating the utterance to have the ability to map the sounds that they
hear
Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditor ...
from the other person's oral pronunciation to similar
places and
manners of articulation in their own
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 ...
.
Such speech input/output imitation often occurs independently of speech comprehension such as in
speech shadowing in which people automatically say words heard in
earphones, and the pathological condition of
echolalia in which people
reflexively repeat overheard words. That links to speech repetition of words being separate in the
brain
A brain is an organ (biology), 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 Visual perception, vision. I ...
to
speech perception. Speech repetition occurs in the dorsal speech processing stream, and speech perception occurs in the ventral speech processing stream. Repetitions are often incorporated unawares by that route into spontaneous novel sentences immediately or after delay after the storage in
phonological memory.
In humans, the ability to map heard input vocalizations into motor output is highly developed because of the copying ability playing a critical role in children's rapid expansion of their
spoken vocabulary. In older children and adults, that ability remains important, as it enables the continued learning of novel words and names and
additional languages. That repetition is also necessary for the propagation of language from generation to generation. It has also been suggested that the phonetic units out of which speech is made have been selected upon by the process of vocabulary expansion and vocabulary
transmissions because children prefer to copy words in terms of more easily-imitated elementary units.
Properties
Automatic
Vocal imitation happens quickly: words can be repeated within 250-300
milliseconds both in normals (during
speech shadowing) and during
echolalia. The imitation of
speech syllables possibly happens even more quickly: people begin imitating the second phone in the syllable
oearlier than they can identify it (out of the set
o æand
i.
Indeed, "...simply executing a shift to
upon detection of a second vowel in
otakes very little longer than does interpreting and executing it as a shadowed response".
Neurobiologically this suggests "...that the early
phases of speech analysis yield information which is directly convertible to information required for speech production".
Vocal repetition can be done immediately as in speech shadowing and echolalia. It can also be done after the pattern of pronunciation is stored in
short-term memory or
long-term memory
Long-term memory (LTM) is the stage of the Atkinson–Shiffrin memory model in which informative knowledge is held indefinitely. It is defined in contrast to short-term and working memory, which persist for only about 18 to 30 seconds. Long-t ...
. It automatically uses both auditory and where available visual information about how a word is produced.
The automatic nature of speech repetition was noted by
Carl Wernicke, the late nineteenth century
neurologist, who observed that "The primary speech movements, enacted before the development of consciousness, are reflexive and mimicking in nature..".
[Wernicke K. The aphasia symptom-complex. 1874. Breslau, Cohn and Weigert. Translated in: Eling P, editor. Reader in the history of aphasia. Vol. 4. Amsterdam: John Benjamins; 1994. p. 69–89. ]
Independent of speech
Vocal imitiation arises in
development before
speech comprehension and also
babbling: 18-week-old
infants
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used ...
spontaneously copy vocal expressions provided the accompanying voice matches. Imitation of
vowels has been found as young as 12 weeks. It is independent of native language, language skills, word comprehension and a speaker's
intelligence
Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can ...
. Many
autistic
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
and some
mentally disabled people engage in the echolalia of overheard words (often their only vocal interaction with others) without understanding what they echo. Reflex uncontrolled echoing of others words and sentences occurs in roughly half of those with
Gilles de la Tourette syndrome. The ability to repeat words without comprehension also occurs in
mixed transcortical aphasia where it links to the sparing of the short-term phonological store.
The ability to repeat and imitate speech sounds occurs separately to that of normal speech. Speech shadowing provides evidence of a 'privileged' input/output speech loop that is distinct to the other components of the speech system.
[McLeod P. Posner MI. (1984). Privileged loops from percept to act. In H. Bouma D. Bouwhuis, (Eds), Attention and performance X (pp. 55-66). Hillsdale, NJ, Erlbaum. ] Neurocognitive research likewise finds evidence of a direct (nonlexical) link between phonological analysis input and motor programming output.
Effector independent
Speech sounds can be imitatively mapped into vocal articulations in spite of vocal tract anatomy differences in size and shape due to
gender
Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most culture ...
,
age and individual
anatomical
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...
variability. Such variability is extensive making input output mapping of speech more complex than a simple mapping of vocal track movements. The shape of the mouth varies widely:
dentist
A dentist, also known as a dental surgeon, is a health care professional who specializes in dentistry (the diagnosis, prevention, management, and treatment of diseases and conditions of the oral cavity and other aspects of the craniofacial c ...
s recognize three basic shapes of
palate: trapezoid, ovoid, and triagonal; six types of
malocclusion between the two
jaws; nine ways teeth relate to the
dental arch and a wide range of
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
ry and
mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
deformities. Vocal sound can also vary due to dental injury and
dental caries. Other factors that do not impede the sensory motor mapping needed for vocal imitation are gross oral deformations such as
hare-lip
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 te ...
s,
cleft palates or amputations of the tongue tip, pipe smoking, pencil biting and teeth clinching (such as in
ventriloquism).
Paranasal sinuses
Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the sph ...
vary between individuals 20-fold in volume, and differ in the presence and the degree of their asymmetry.
Diverse linguistic vocalizations
Vocal imitation occurs potentially in regard to a diverse range of phonetic units and types of vocalization. The world's languages use
consonantal phones that differ in thirteen imitable vocal tract
place of articulations (from the
lips to the
glottis
The glottis is the opening between the vocal folds (the rima glottidis). The glottis is crucial in producing vowels and voiced consonants.
Etymology
From Ancient Greek ''γλωττίς'' (glōttís), derived from ''γλῶττα'' (glôtta), v ...
). These phones can potentially be pronounced with eleven types of imitable
manner of articulation
In articulatory phonetics, the manner of articulation is the configuration and interaction of the articulators ( speech organs such as the tongue, lips, and palate) when making a speech sound. One parameter of manner is ''stricture,'' that is ...
s (
nasal stop
In phonetics, a nasal, also called a nasal occlusive or nasal stop in contrast with an oral stop or nasalized consonant, is an occlusive consonant produced with a lowered velum, allowing air to escape freely through the nose. The vast majori ...
s to
lateral clicks). Speech can be copied in regard to its
social accent,
intonation,
pitch and individuality (as with entertainment
impersonator
An impersonator is someone who imitates or copies the behavior or actions of another. There are many reasons for impersonating someone:
*Entertainment: An entertainer impersonates a celebrity, generally for entertainment, and makes fun of ...
s). Speech can be articulated in ways which diverge considerably in speed,
timbre, pitch,
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 ...
and
emotion
Emotions are mental states brought on by neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or displeasure. There is currently no scientific consensus on a definitio ...
. Speech further exists in different forms such as
song
A song is a musical composition intended to be performed by the human voice. This is often done at distinct and fixed pitches (melodies) using patterns of sound and silence. Songs contain various forms, such as those including the repetiti ...
,
verse,
scream and
whisper
Whispering is an unvoiced mode of phonation in which the vocal cords are abducted so that they do not vibrate; air passes between the arytenoid cartilages to create audible turbulence during speech. Supralaryngeal articulation remains the ...
. Intelligible speech can be produced with pragmatic intonation and in
regional dialects and
foreign accents. These aspects are readily copied: people asked to repeat speech-like words imitate not only phones but also accurately other pronunciation aspects such as
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 ...
,
schwa
In linguistics, specifically phonetics and phonology, schwa (, rarely or ; sometimes spelled shwa) is a vowel sound denoted by the IPA symbol , placed in the central position of the vowel chart. In English and some other languages, it rep ...
-syllable expression,
voice
spectra and lip
kinematic
Kinematics is a subfield of physics, developed in classical mechanics, that describes the motion of points, bodies (objects), and systems of bodies (groups of objects) without considering the forces that cause them to move. Kinematics, as a fie ...
s,
voice onset times, and
regional accent.
Language acquisition
Vocabulary expansion
In 1874 Carl Wernicke proposed that the ability to imitate speech plays a key role in language acquisition. This is now a widely researched issue in
child development.
[Miller GA. (1977). Spontaneous apprentices: Children and language. New York, Seabury Press. ][PDF]
A study of 17,000 one and two word utterances made by six children between 18 months to 25 months found that, depending upon the particular
infant
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used t ...
, between 5% and 45% of their words might be mimicked.
These figures are minima since they concern only immediately heard words. Many words that may seem spontaneous are in fact delayed imitations heard days or weeks previously.
At 13 months children who imitate new words (but not ones they already know) show a greater increase in
noun
A noun () is a word that generally functions as the name of a specific object or set of objects, such as living creatures, places, actions, qualities, states of existence, or ideas.Example nouns for:
* Living creatures (including people, alive, ...
vocabulary at four months and non noun vocabulary at eight months.
A major predictor of vocabulary increase in both 20 months, 24 months,
and older children between 4 and 8 years is their skill in repeating nonword phone sequences (a measure of mimicry and storage).
This is also the case with children with
Down's syndrome . The effect is larger than even age: in a study of 222 two-year-old children that had spoken vocabularies ranging between 3–601 words the ability to repeat nonwords accounted for 24% of the
variance
In probability theory and statistics, variance is the expectation of the squared deviation of a random variable from its population mean or sample mean. Variance is a measure of dispersion, meaning it is a measure of how far a set of numbe ...
compared to 15% for age and 6% for
gender
Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most culture ...
(girls better than boys).
Nonvocabulary expansion uses of imitation
Imitation provides the basis for making longer sentences than children could otherwise spontaneously make on their own. Children analyze the
linguistic rules,
pronunciation patterns, and conversational
pragmatics
In linguistics and related fields, pragmatics is the study of how context contributes to meaning. The field of study evaluates how human language is utilized in social interactions, as well as the relationship between the interpreter and the int ...
of speech by making
monologues (often in
crib talk) in which they repeat and manipulate in
word play
Word play or wordplay (also: play-on-words) is a literary technique and a form of wit in which words used become the main subject of the work, primarily for the purpose of intended effect or amusement. Examples of word play include puns, pho ...
phrases and sentences previously overheard. Many proto-conversations involve children (and parents) repeating what each other has said in order to sustain social and linguistic interaction. It has been suggested that the conversion of speech sound into motor responses helps aid the vocal "alignment of interactions" by "coordinating the rhythm and melody of their speech". Repetition enables immigrant monolingual children to learn a second language by allowing them to take part in 'conversations'. Imitation related processes aids the storage of overheard words by putting them into speech based short- and long-term memory.
Language learning
The ability to repeat nonwords predicts the ability to learn second-language vocabulary. A study found that adult
polyglots performed better in short-term memory tasks such as repeating nonword vocalizations compared to nonpolyglots though both are otherwise similar in general intelligence, visuo-spatial short-term memory and paired-associate learning ability.
Language delay
A language delay is a language disorder in which a child fails to develop language abilities at the usual age-appropriate period in their developmental timetable. It particularly affects deaf children who are denied sign language. It is most co ...
in contrast links to impairments in vocal imitation.
Speech repetition and phones
Electrical brain stimulation research upon the human brain finds that 81% of areas that show disruption of phone identification are also those in which the imitating of oral movements is disrupted and vice versa;
Brain injuries
Neurotrauma, brain damage or brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating ...
in the speech areas show a 0.9 correlation between those causing impairments to the copying of oral movements and those impairing phone production and perception.
Mechanism
Spoken words are sequences of motor movements organized around vocal tract gesture motor targets. Vocalization due to this is copied in terms of the motor goals that organize it rather than the exact movements with which it is produced. These vocal motor goals are auditory. According to James Abbs 'For speech motor actions, the individual articulatory movements would not appear to be controlled with regard to three- dimensional spatial targets, but rather with regard to their contribution to complex vocal tract goals such as resonance properties (e.g., shape, degree of constriction) and or aerodynamically significant variables'. Speech sounds also have duplicable higher-order characteristics such as rates and shape of modulations and rates and shape of frequency shifts. Such complex auditory goals (which often link—though not always—to internal vocal gestures) are detectable from the speech sound which they create.
Neurology
Dorsal speech processing stream function
Two cortical processing streams exist: a ventral one which maps sound onto meaning, and a dorsal one, that maps sound onto motor representations. The dorsal stream projects from the posterior
Sylvian fissure at the
temporoparietal junction
The temporoparietal junction (TPJ) is an area of the brain where the temporal lobe, temporal and parietal lobe, parietal lobes meet, at the posterior end of the lateral sulcus (Sylvian fissure). The TPJ incorporates information from the thalamus a ...
, onto frontal motor areas, and is not normally involved in speech perception.
Carl Wernicke identified a pathway between the left posterior
superior temporal sulcus (a cerebral cortex region sometimes called the
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 ...
) as a centre of the sound "images" of speech and its syllables that connected through 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' ...
with part of the
inferior frontal gyrus (sometimes called the
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 Pier ...
) responsible for their articulation.
This pathway is now broadly identified as the dorsal speech pathway, one of the two pathways (together with the ventral pathway) that process speech. The posterior
superior temporal gyrus
The superior temporal gyrus (STG) is one of three (sometimes two) gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.
The superior temporal gyrus is bounded by:
* the l ...
is specialized for the transient representation of the phonetic sequences used for vocal repetition. Part of the
auditory cortex also can represent aspects of speech such as its consonantal features.
Mirror neurons
Mirror neurons have been identified that both process the perception and production of motor movements. This is done not in terms of their exact motor performance but an inference of the intended motor goals with which it is organized. Mirror neurons that both perceive and produce the motor movements of speech have been identified. Speech is mirrored constantly into its articulations since speakers cannot know in advance that a word is unfamiliar and in need of repetition—which is only learnt after the opportunity to map it into articulations has gone. Thus, speakers if they are to incorporate unfamiliar words into their spoken vocabulary
must by default map all spoken input.
Sign language
Words in
sign languages
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 ...
, unlike those in spoken ones, are made not of sequential units but of
spatial configurations of subword unit arrangements, the spatial analogue of the sonic-chronological
morpheme
A morpheme is the smallest meaningful Constituent (linguistics), constituent of a linguistic expression. The field of linguistics, linguistic study dedicated to morphemes is called morphology (linguistics), morphology.
In English, morphemes are ...
s of spoken language.
[Poizner H. Klima ES. Bellugi U. (1987). What the hands reveal about the brain. MIT Press. ] These words, like spoken ones, are learnt by imitation. Indeed, rare cases of compulsive sign-language echolalia exist in otherwise language-deficient deaf autistic individuals born into signing families.
At least some cortical areas neurobiologically active during both sign and vocal speech, such as the auditory cortex, are associated with the act of imitation.
Nonhuman animals
Birds
Bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s learn their
song
A song is a musical composition intended to be performed by the human voice. This is often done at distinct and fixed pitches (melodies) using patterns of sound and silence. Songs contain various forms, such as those including the repetiti ...
s from those made by other birds. In several examples, birds show highly developed repetition abilities: the Sri Lankan
Greater racket-tailed drongo (''Dicrurus paradiseus'') copies the calls of predators and the
alarm signals of other birds
Albert's lyrebird (''Menura alberti'') can accurately imitate the
satin bowerbird (''Ptilonorhynchus violaceus''),
Research upon
avian vocal motor neurons finds that they perceive their song as a series of articulatory gestures as in humans. Birds that can imitate humans, such as the Indian
hill myna
''Gracula'' is a genus of mynas, tropical members of the starling family of birds found in southern Asia and introduced to Florida in the United States.
Taxonomy
The genus ''Gracula'' was introduced in 1758 by the Swedish naturalist Carl Linnaeu ...
(Gracula religiosa), imitate human speech by mimicking the various speech
formants, created by changing the shape of the human vocal tract, with different vibration frequencies of its
internal tympaniform membrane.
Indian hill mynahs also imitate such phonetic characteristics as
voicing,
fundamental frequencies,
formant transitions,
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 ...
, and timing, through their vocal movements are made in a different way from those of the human vocal apparatus.
Nonhuman mammals
*
Bottlenose dolphins can show spontaneous vocal mimicry of computer-generated whistles.
*
Killer whales can mimic the barks of
California sea lion
The California sea lion (''Zalophus californianus'') is a coastal eared seal native to western North America. It is one of six species of sea lions. Its natural habitat ranges from southeast Alaska to central Mexico, including the Gulf of Ca ...
s.
*
Harbor seal
The harbor (or harbour) seal (''Phoca vitulina''), also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared se ...
s can mimic in a speech-like manner one or more English words and phrases
*
Elephants
Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae ...
can
imitate trunk sounds.
*
Lesser spear-nosed bat
The lesser spear-nosed bat (''Phyllostomus elongatus'') is a bat species found in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, Re ...
can learn their call structure from artificial playback.
* An
orangutan
Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...
has spontaneously copied the
whistles of humans.
Apes
Apes taught language show an ability to imitate language signs with
chimpanzee
The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative t ...
s such as
Washoe who was able to learn with his arms a vocabulary of 250
American Sign Language gestures. However, such human trained apes show no ability to imitate human speech vocalizations.
[Hayes C. (1951). The ape in our house, Harper, New York. ]
See also
*
Alan Baddeley
*
Auditory processing disorder
*
Baddeley's model of working memory
Baddeley's model of working memory is a model of human memory proposed by Alan Baddeley and Graham Hitch in 1974, in an attempt to present a more accurate model of primary memory (often referred to as short-term memory). Working memory splits p ...
*
Conduction aphasia
Conduction aphasia, also called associative aphasia, is an uncommon form of difficulty in speaking (aphasia). It is caused by damage to the parietal lobe of the brain. An acquired language disorder, it is characterised by intact auditory comprehe ...
*
Developmental verbal dyspraxia
*
Echoic memory
*
Echolalia
*
Language development
*
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 ...
*
Language-based learning disability
*
Mirror neurons
*
Mirroring (psychology)
Mirroring is the behavior in which one person subconsciously imitates the gesture, speech pattern, or attitude of another. Mirroring often occurs in social situations, particularly in the company of close friends or family, often going unnotice ...
*
Motor cognition
*
Motor theory of speech perception
*
Origin of language
The origin of language (spoken and signed, as well as language-related technological systems such as writing), its relationship with human evolution, and its consequences have been subjects of study for centuries. Scholars wishing to study th ...
*
Passive speakers
*
Phonological development
*
Pronunciation
Pronunciation is the way in which a word or a language is spoken. This may refer to generally agreed-upon sequences of sounds used in speaking a given word or language in a specific dialect ("correct pronunciation") or simply the way a particular ...
*
Second-language acquisition
*
Short-term memory
*
Speech perception
*
Thematic coherence
*
Transcortical motor aphasia
*
Transcortical sensory aphasia
*
Vocabulary growth
*
Vocal learning
Footnotes
{{reflist, 2
Developmental psychology
Evolution of language
Language
Language acquisition
Motor control
Phonetics
Speech and language pathology
Speech recognition
Speech