Tonal cues to prosodic structure in rate-dependent speech perception.

ABSTRACT

This study explores how listeners integrate tonal cues to prosodic structure with their perception of local speech rate and consequent interpretation of durational cues. In three experiments, we manipulate the pitch and duration of speech segments immediately preceding a target sound along a vowel duration continuum (cueing coda stop voicing), testing how listeners' categorization of vowel duration shifts based on temporal and tonal context. We find that listeners perceive the presence of a phrasal boundary tone on a lengthened syllable as signaling a slowdown in speech rate, shifting perception of vowel duration, with effects that are additive when crossed in a 2 × 2 (pitch × duration) design. However, an asymmetrical effect of pitch and duration is found in an explicit duration judgement task in which listeners judge how long a pre-target syllable sounds to them. In explicit rate judgement, only durational information is consequential, unlike the categorization task, suggesting that integration of tonal and durational prosodic cues in rate-dependent perception is limited to implicit processing of speech rate. Results are discussed in terms of linguistic information in rate-dependent speech processing, the integration of prosodic cues, and implicit and explicit rate processing tasks.