Yoonsook Mo, Jennifer Cole, and Mark Hasegawa-Johnson, University of Illinois
Prosody serves an important function in speech communication: prosodic phrasing groups words into pragmatically and semantically coherent smaller chunks and prosodic prominence encodes the discourse-level status and rhythmic structure of a word within a phrase. Acoustic cues to prosody are available from the speech signal and can be used by listeners to recover the pragmatic and discourse meaning intended by speakers. Effects of prosodic context on the duration of consonants and vowels have been widely reported, and this study extends that line of work by examining how prosodic phrase boundary and prominence influence the temporal structure of the monosyllabic CVC word, based on an analysis of speech excerpts from the Buckeye corpus of spontaneous conversational American English. Prosody annotation for these speech materials is obtained from 97 untrained, non-expert listeners. The results confirm findings from prior studies, showing that (1) monosyllabic CVC words are lengthened before a prosodic phrase boundary and under prominence, and (2) all subcomponents of a syllable, that is, the onset, nucleus, and coda of the monosyllabic word, are elongated. The findings further show that (3) the magnitude of lengthening associated with prosody varies as a function of syllable position, and (4) the magnitude of lengthening of subcomponents of monosyllabic CVC words varies as a function of prosodic characteristics. Nucleus duration is most strongly affected by both prosodic prominence and boundary and the onset and the coda of the monosyllabic word is also affected but to a lesser degree. The lengthening effect of prosodic phrase boundary on the coda is larger than the lengthening effect on onset duration while lengthening of the onset under prosodic prominence is larger than lengthening of the coda. The findings indicate that prosodic context shapes the internal temporal structure of the monosyllabic CVC word.