title: A proposed mechanism for rapid adaptation to spectrally distorted speech.
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.
authors.affiliation: Cognitive Neuroscience Sector, SISSA (International School for Advanced Studies), Via Beirut 2-4, Trieste, Italy.
authors.forename: Mahan
authors.initials: M
authors.lastname: Azadpour
authors.affiliation: Cognitive Neuroscience Sector, SISSA (International School for Advanced Studies), Via Beirut 2-4, Trieste, Italy.
authors.forename: Evan
authors.initials: E
authors.lastname: Balaban
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D032882:Comprehension / Q000502:physiology; D003463:Cues; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D010469:Perceptual Distortion / Q000502:physiology; D010700:Phonetics; D013018:Sound Spectrography; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult