Interaction between duration, context, and speaking style in English stressed vowels

TLDR

The study builds on Lindblom’s vowel undershoot model, which derives formant patterns from locus‑target distance, vowel duration, and rate of formant frequency change. Five speakers produced front vowels in clear and citation‑form styles at varying durations while maintaining a constant speaking rate. Formant patterns were displaced toward adjacent consonants, with the magnitude depending on vowel duration; this context‑duration effect was weaker in clear speech, which compensated by faster formant change, supporting a revised biomechanically motivated vowel undershoot model. Soc.

Abstract

Acoustic observations are reported for English front vowels embedded in a /w—l/ frame and carrying constant main stress. The vowels were produced by five speakers in clear and citation-form styles at varying durations but at a constant speaking rate. The acoustic analyses revealed (i) that formant patterns were systematically displaced in the direction of the frequencies of the consonants of the adjacent pseudosymmetrical context; (ii) that those displacements depended in a lawful manner on vowel duration; (iii) that this context and duration dependence was more limited for clear than for citation-form speech, and that the smaller formant shifts of clear speech tended to be achieved by increases in the rate of formant frequency change. The findings are compatible with a revised, and biomechanically motivated, version of the vowel undershoot model [Lindblom, J. Acoust. Soc. Am. 35, 1773–1781 (1963)] that derives formant patterns from numerical information on three variables: The ‘‘locus-target’’ distance, vowel duration, and rate of formant frequency change. The results further indicate that the ‘‘clear’’ samples were not merely louder, but involved a systematic, undershoot-compensating reorganization of the acoustic patterns.