Lecture Fourteen Speech Perception

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Lecture Fourteen Speech Perception

• Orienting question
• Critically assess motor theory of speech
  perception

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Chomsky-Skinner debate that raging at this
time Unique aspect of speech we produce the
signals that we perceive Leads to many different
renditions for the same speech sound that we have
to perceive Accent Speaker differences
(gender) Speech rate Context differences in
/s/s in /si/ and /su/
Linked theory Production system guides the
perceptual system Contrasts with feedback
monitoring Both cannot be correct Notion that
speech is special Consistent with the climate of
opinion at the time Hemispheric differences in
language processing (left hemisphere and
language lesions, ear differences)
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Unlike the perceptual events, motor organisation
seems constant Plosives in bilabials always
bring the lips together Constancy in
articulatory movements over all different ways of
producing a sound Shown in early work on EMG
measures (later work has shown it is more complex
than this) Motor theory when listen to speech
read it from the way it was produced and then
interpret it perceptually Example the sound Im
hearing involved stoppage of airflow, the lips
were brought together and the sound involved
vocal fold vibration. Therefore it was a /b/
sound. Similarities with Gibsons theory of
perception Advantage one mechanism used for
production and perception (economy) But need two
mechanisms for sound perception one for speech
and one for non-speech.
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Evidence that speech perception is special
(i.e. requires a separate mechanism from other
sounds) Categorical perception Synthetic speech
continuum Labelling Discrimination ABX
task Results with speech Sharp labeling
function Chance discrimination within a phoneme
category Discrimination peak at phoneme
boundary Explanation involving using phoneme
labels (only available for speech sounds)
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Problems Non-speech sound continua are also
categorically perceived Animals (cannot speak)
perceive speech sound continua categorically
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References Howell, P., Harvey, N. (1983).
Perceptual equivalence and motor equivalence in
speech. In B. Butterworth (Ed.), Language
Production, Vol. 2, 203-224. Academic
Press. Rosen, S., Howell, P. (1987).
Auditory, articulatory and learned factors in
categorical perception. In Categorical
Perception. Pp. 113-160. S. Harnad (Ed.). New
York Cambridge University Press.