Control of vocal-tract length in speech

Abstract

Essential for the correct production of vowels is the accurate control of vocal‐tract length. Perkell [P s y c h o l o g y o f S p e e c h P r o d u c t i o n (MIT, Cambridge, MA, 1969)] has suggested that two important determinants of vocal‐tract length are vertical larynx position and lip spreading/protrusion, often acting together. The present study was designed to determine whether constraining lip spreading/protrusion induces 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. Significant differences were found in upper‐lip protrusion and larynx position depending on the vowel uttered. Moreover, the generally low‐larynx position of rounded vowels became even lower when lip protrusion was constrained. These results imply that compensatory articulations contribute to a contrast‐preserving strategy in speech production.