Categorical or continuous speech perception: A new test

Abstract

An important question in speech perception is whether listeners have continuous or categorical information about the acoustic signal in speech. Most traditional experimental studies have been interpreted as evidence for categorical perception. It is also argued in the present paper that more recent results taken as evidence against categorical perception are not unequivocally negative. Accordingly, further tests between continuous and categorical views of speech perception are necessary. In the present experiments, listeners were asked for continuous rather than discrete judgments in order to provide a more direct answer to this question. Subjects were asked to rate speech sounds according to where they fell on a particular speech continuum. The continua consisted of stop consonants varying in place (/bæ/to/dæ/) or voicing (/bæ/to/pæ/) or a vowel continuum varying from /i/to/I/. The distributions of rating responses of individual subjects were used to test quantitative models of categorical and continuous perception of acoustic features in speech. The results provide strong evidence against the categorical perception of speech contrasts, and contribute additional evidence for the role of continuous acoustic feature information in speech processing.