Phonological constraints in speech perception

An important question in speech perception research is whether or not listeners have information about the degree to which an acoustic feature is present in speech. Evidence from traditional experimental studies of categorical perception suggests a negative answer for some speech sounds. 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 (/ba/ to /da/) or voicing (/ba/ to /pa/) or a vowel continuum varying from /i/ to /I/. The rating responses of individual subjects were used to test quantitative models of “categorical” and “continuous” perception of acoustic features in speech. [Work supported by NIMH.]