Adaptation of the category boundary between speech and nonspeech: A consonantal case against feature detectors
Robert E. Remez · The Journal of the Acoustical Society of America · 1979
Feature detector accounts of speech perception propose that the distinctive features of phonetic analysis define the inventory of perceptual analyzers. In a recent test of this model, the perceptual boundary between a speech and a nonspeech sound was found to undergo adaptation comparable to adaptation of phonetic categories. A feature detector account of this finding requires the implausible extension of the detector inventory to include nonspeech features. This finding therefore offered counterevidence to the detector model. However, the use of vowels as the speech sound suggests that the test may not be valid, given the relative “nonspeech” quality of vowels judged on a variety of perceptual criteria. The present experiment answers this criticism by using synthetic stimuli ranging from the CV /ba/ to a nonspeech buzz in the adaptation paradigm. The stimuli were made by varying the bandwidths of the five formants, from 200 to 650 Hz in 50-Hz steps. The predicted boundary shifts occur in this case, corroborating the original argument against phonetic feature detectors. It would appear, then, that these results undermine the rationale for phonetic feature detectors in speech perception. [Supported by NIMH.]