Lip and jaw closing gesture durations in syllable final voiced and voiceless stops

Abstract

It is generally assumed that the longer vowel durations in voiced final consonant contexts can be attributed to longer vowel steady state durations wherein the jaw remains stable for a longer period of time (see diagrams in Chen, 1970; Summers, 1987). Chen (1970) argued that the rate of closure duration was the best explanation for the vowel length effect. However, the closure durational differences he reported were very small relative to the reported differences in vowel duration with an average of 17 ms to 92 ms. Lip and jaw movements for two speakers were measured and synchronized with acoustic data in the CSD department at the University of Texas using the head-mounted lip-jaw movement transducer (HMLJMT) of Barlow et al. (1983). This study provides much stronger evidence for Chen’s hypothesis, suggesting that there is a more dynamic arc to the jaw. While Chen (1970) gave data showing the closing gesture accounted for less than 20% of the overall difference, the data given here, shows that the duration of the closing gesture can account for 80% of the total vowel durational differences, and the remainder can be accounted for in the opening gesture and the relative timing of vocal cord cessation.