The Relative Roles of Syntax and Prosody in the Perception of the /š/ -/č/ Distinction

Abstract

A silent interval that cues the /š/-/č/ distinction in many contexts is less likely to do so when it coincides with certain boundaries. In natural speech these boundaries are generally marked by both prosody and syntax. We independently varied syntax and prosody to assess their contributions to the phonetic interpretation of silences occurring at these boundaries. We used a set of four sentences, four durations of silence, and two prosodic patterns (Experiment I). We constructed sentences using three techniques that differed in the amount of prosodic control and in naturalness: synthesis by rule, concatenation of naturally produced syllables, and cross-splicing of naturally produced utterances. Silence duration had a strong effect on the perception of the /š/-/č/ contrast in all conditions. For the Synthetic Condition, we also found a strong effect of the prosodic pattern. We found no evidence of any purely syntactic effect. In Experiment II, the two syllables surrounding the silence were excised from the sentences of Experiment I and presented to listeners for labeling. Prosody had a significant effect in the Synthetic Condition and in the Natural Condition. The results indicate that the local prosodic pattern (one syllable with a pitch fall and a greater length) can be sufficient to influence listeners' perception of the /š/-/č/ contrast. There is also evidence that the prosodic information may be subject to context effects.