Auditoryacoustic relations and effects on language inventory

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Auditory-acoustic relations and effects on
language inventory
Carrie Niziolek carrien 24.922 5 may 2004
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Introduction

• Quantal relations both acoustic-articulatory and
  auditory-acoustic.
• How does the peripheral auditory system shape
  responses to acoustics?
• How does the central auditory system amplify
  learned contrasts?

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Purpose of report

• to address feature constraints imposed by the
  auditory system
• to address perceptibility as a tool for guiding
  feature constraints in a language
• Does perceptibility (and, by extension,
  quantalness) affect survival in a language?

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Categorical perception

• A continuous change in a variable is perceived as
  instances of discrete categories
• Between-cat discrimination is better than
  within-cat discrimination (enhanced category
  boundaries)
• CP is induced through category learning, or
  merely acoustic exposure

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Speech perception

• Motor theory phonemes are processed by special
  phonetic mechanisms of hearing (learned internal
  lang-production model)
• Preverbal infants and nonverbal animals share
  categorical perception boundaries
• What decoding processes do our auditory systems
  have in common?

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Feature constraints

• Auditory system needs 20 ms to perceive temporal
  ordering (less than 20 ms one auditory event?)

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Auditory-acoustic relations

• Eimas et al. (1971) used a bilabial VOT continuum
  to show that English infants better discriminate
  across-boundary stimuli
• Eilers et al. (1979) showed that Spanish infants
  also have greatest sensitivity across the English
  boundary
• Evidence for an auditorily-determined boundary
• Do more languages have an English-like boundary
  than not?

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Non-speech aud-acoust relations

• Non-linear acoustic to auditory mapping natural
  auditory sensitivities

Use sawtooth waves to test perception plucks or
bows?
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Non-speech aud-acoust relations

• Non-linear acoustic to auditory mapping natural
  auditory sensitivities
• Large-target regions small variations
• Thresholds, regions of instability (40ms)

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Range effects

• Input range affects perception is boundary
  merely at midpoint of range?

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Perceptibility in Turkish

• Turkish h deletion
• Occurs in contexts where lower perceptibility is
  predicted
• Speech taking advantage of perceptual constraints

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Mispronunciation detection

• Percent detection increases as number of features
  change
• How do subjects integrate these features?

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Optimizing language contrasts

• Language evolution will tend to converge on
  maximally distinct phonemes
• Maximize perceptual distance vowel dispersion
• Maximize ease of articulation find a stable
  acoustic region that allows for a relatively
  imprecise gesture

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Vowel dispersion

• Predicts the optimization of acoustic structure
  of vowel inventory maximize inter-vowel contrast

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References

• Stevens K. On the quantal nature of speech. J.
  Phonetics (1989) 17, 3-45.
• Harnad, S. Psychophysical and cognitive aspects
  of categorical perception A critical overview,
  in Harnad, Stevan, Eds. Categorical Perception
  The Groundwork of Cognition (1987), chapter 1,
  pages pp. 1-52. Cambridge University Press.
• Howell, P. Rosen, S. (1984) Natural auditory
  sensitivities as universal determiners of
  phonemic contrasts. Linguistics 211 205-235
• Kuhl PK and Miller JD Speech perception by the
  chinchilla. Science, 190 69-72. 1975.
• Mielke J. The interplay of speech perception and
  phonology experimental evidence from Turkish.
  Phonetica 2003 Jul-Sep60(3)208-29.
• Gao E, Suga N. Experience-dependent corticofugal
  adjustment of midbrain frequency map in bat
  auditory system. Neurobiology 1998
  Oct95(21)12663-12670.

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Neural measures of perception

• Lateral posterior STG
• Acoustic-phonetic processing activation from
  words, pseudowords, and reversed speech
• Not critical for discrimination of non-speech
  auditory stimuli (tones, noise)
• Disputed other human vocalizations? (coughing)
• Anterior STG
• Inferior frontal cortex

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Organization of speech circuits

• Model of functional circuits that are critical
  for speech perception
• Functional subdivisions in left STG
• Anterior STG
• Posterior phonological
• Anterior sentence processing
• Posterior STG
• Anterior acoustic-phonetic
• Posterior phonological
• Temporoparietal junction lexical-semantic

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Organization of speech circuits

• Hierarchical organization
• Acoustic-phonetic processing local posterior
  network
• Increasingly distributed networks as processing
  becomes more complex
• Modular and distributed cortical circuits

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Cortical perception

• Acoustic-phonetic processes localized to the
  middle-posterior region of left STG
• Increased cortical distribution for higher-level
  speech perception tasks
• Dissociation implies functional subdivisions,
  hierarchical organization

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Corticofugal pathways

• i.e., how the cortex affects processing in lower
  auditory centers
• Acoustic cues enhanced or suppressed
• Positive feedback to subcortical neurons
  matched in tuning to an acoustic parameter
• Lateral inhibition to unmatched neurons