A proposed mechanism for rapid adaptation to spectrally distorted speech Articles uri icon

authors

  • AZADPOUR, MAHAN
  • BALABAN, EVAN STUART

publication date

  • July 2015

start page

  • 44

end page

  • 57

issue

  • 1

volume

  • 138

International Standard Serial Number (ISSN)

  • 0001-4966

Electronic International Standard Serial Number (EISSN)

  • 1520-8524

abstract

  • The mechanisms underlying perceptual adaptation to severely spectrally-distorted speech were studied by training participants to comprehend spectrally-rotated speech, which is obtained by inverting the speech spectrum. Spectral-rotation produces severe distortion confined to the spectral domain while preserving temporal trajectories. During five 1-hour training sessions, pairs of participants attempted to extract spoken messages from the spectrally-rotated speech of their training partner. Data on training-induced changes in comprehension of spectrally-rotated sentences and identification/discrimination of spectrally-rotated phonemes were used to evaluate the plausibility of three different classes of underlying perceptual mechanisms: (1) phonemic remapping (the formation of new phonemic categories that specifically incorporate spectrally-rotated acoustic information); (2) experience-dependent generation of a perceptual 'inverse-transform” that compensates for spectral-rotation; and (3) changes in cue weighting (the identification of sets of acoustic cues least affected by spectral-rotation, followed by a rapid shift in perceptual emphasis to favour those cues, combined with the recruitment of the same type of 'perceptual filling-in” mechanisms used to disambiguate speech-in-noise). Results exclusively support the third mechanism, which is the only one predicting that learning would specifically target temporally-dynamic cues that were transmitting phonetic information most stably in spite of spectral-distortion. No support was found for phonemic remapping or for inverse-transform generation.

subjects

  • Biology and Biomedicine
  • Psychology

keywords

  • speech communication; phonetics; human voice; acoustics; hearing; speech analysis; speech processing systems; consonants; vowel systems; neuroanatomy