Discrimination of F2 Transitions in Speech Context and in Isolation

Parallel tests suggest that perception of a stop‐consonant cue depends on whether the cue is presented in a speed]like context or in isolation. Subjects were asked to label as /bae/, /dae/, or /gae/ two‐formant synthetic speech stimuli differing only in the initial F2 transition, to discriminate between pairs of these stimuli, and to discriminate between corresponding pairs of isolated F2 transitions. A subject's discrimination function for transitions in speech context typically shows two sharp peaks, matching the crossover points of his three labeling functions; these peaks at phoneme boundaries exhibit little intersubject variation. For the isolated transitions, the two peaks that characterize the speech functions are absent; such peaks as do occur are generally lower and more variable, both in position and height. Evidently, the discrimination peaks that occur at the phoneme boundaries are not inherent in the perception of the F2 transition itself. [Support by ONR, NICHD, and VA is acknowledged.]