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Auditory-acoustic relations and effects on language inventory

Auditory-acoustic relations and effects on language inventory. Carrie Niziolek [carrien] 24.922 5 may 2004. Introduction. Quantal relations both acoustic-articulatory and auditory-acoustic . How does the peripheral auditory system shape responses to acoustics?

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Auditory-acoustic relations and effects on language inventory

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  1. Auditory-acoustic relations and effects on language inventory Carrie Niziolek [carrien] 24.922 5 may 2004

  2. 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?

  3. 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?

  4. 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

  5. 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?

  6. Feature constraints • Auditory system needs 20 ms to perceive temporal ordering (less than 20 ms = one auditory event?)

  7. 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?

  8. Non-speech aud-acoust relations • Non-linear acoustic to auditory mapping: natural auditory sensitivities Use sawtooth waves to test perception: plucks or bows?

  9. Non-speech aud-acoust relations • Non-linear acoustic to auditory mapping: natural auditory sensitivities • Large-target regions: small variations • Thresholds, regions of instability (~40ms)

  10. Range effects • Input range affects perception: is boundary merely at midpoint of range?

  11. Perceptibility in Turkish • Turkish [h] deletion • Occurs in contexts where lower perceptibility is predicted • Speech taking advantage of perceptual constraints

  12. 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

  13. 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. Linguistics211: 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-Sep;60(3):208-29. • Gao E, Suga N. Experience-dependent corticofugal adjustment of midbrain frequency map in bat auditory system. Neurobiology 1998 Oct;95(21):12663-12670.

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

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