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Abstract

Speech is remarkably variable: ask 10 talkers to pronounce the same sentence and you’ll end up with 10 unique, acoustically dissimilar realizations. One way in which the listener copes with this acoustic variability is by normalizing speech segments for surrounding temporal and spectral characteristics. That is, a given speech sound can be perceived differently depending on, for instance, the preceding sentence’s speech rate, or average formant values. I will present evidence that these normalization processes occur very early in perceptual processing. Also, using neuroimaging and psychoacoustic data, I will show that temporal normalization may be explained by a neural mechanism involving cortical theta oscillators phase-locking to the syllabic rate of speech. Thus, I propose a neurobiologically plausible model of acoustic normalization in speech processing.