Speech repetition
In older children and adults, that ability remains important, as it enables the continued learning of novel words and names and additional languages.
Many autistic and some mentally disabled people engage in the echolalia of overheard words (often their only vocal interaction with others) without understanding what they echo.
[9][10][11][12] Reflex uncontrolled echoing of others words and sentences occurs in roughly half of those with Gilles de la Tourette syndrome.
[13] 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.
[15] Neurocognitive research likewise finds evidence of a direct (nonlexical) link between phonological analysis input and motor programming output.
Other factors that do not impede the sensory motor mapping needed for vocal imitation are gross oral deformations such as hare-lips, cleft palates or amputations of the tongue tip, pipe smoking, pencil biting and teeth clinching (such as in ventriloquism).
The world's languages use consonantal phones that differ in thirteen imitable vocal tract place of articulations (from the lips to the glottis).
These phones can potentially be pronounced with eleven types of imitable manner of articulations (nasal stops to lateral clicks).
[25] In 1874 Carl Wernicke proposed[26] that the ability to imitate speech plays a key role in language acquisition.
[35] Children analyze the linguistic rules, pronunciation patterns, and conversational pragmatics of speech by making monologues (often in crib talk) in which they repeat and manipulate in word play phrases and sentences previously overheard.
[38] Imitation related processes aids the storage of overheard words by putting them into speech based short- and long-term memory.
According to James Abbs[46] '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'.
The dorsal stream projects from the posterior Sylvian fissure at the temporoparietal junction, onto frontal motor areas, and is not normally involved in speech perception.
[48] Carl Wernicke identified a pathway between the left posterior superior temporal sulcus (a cerebral cortex region sometimes called the Wernicke's area) as a centre of the sound "images" of speech and its syllables that connected through the arcuate fasciculus with part of the inferior frontal gyrus (sometimes called the Broca's area) responsible for their articulation.
Indeed, rare cases of compulsive sign-language echolalia exist in otherwise language-deficient deaf autistic individuals born into signing families.
[55] 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.
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[57] Albert's lyrebird (Menura alberti) can accurately imitate the satin bowerbird (Ptilonorhynchus violaceus),[58] Research upon avian vocal motor neurons finds that they perceive their song as a series of articulatory gestures as in humans.
