Control of vocal tract length in speech

Abstract

Accurate control of vocal tract length is essential for the correct production of vowels. Vertical larynx movement and lip spreading/protrusion, often acting together, are important determinants of vocal tract length. The present study was designed to determine whether constraining lip spreading/protrusion will induce compensatory vertical larynx displacements, particularly on rounded vowels. Upper lip and larynx movement were monitored photoelectrically while French and Mandarin native speakers produced the vowels /i, y, u/ first under normal speech conditions and then with lip activity constrained. In agreement with the findings of Sundberg (1969), Benguerel (1974), and Ewan (1976), there were significant differences during normal speech in upper lip protrusion and larynx position as a function of the vowel and tone uttered, in particular a difference in lip protrusion between /u/ and /y/. Results further reveal that the generally low larynx position of rounded vowels becomes even lower than lip protrusion is constrained. This data has implications for the role of a contrast-preserving strategy in speech production. [Supported in part by the National Science Foundation. ] Also, Department of Languages and Linguistics, University of Essex, Colchester, England.