ASA 127th Meeting M.I.T. 1994 June 6-10

1pSP33. Kinematic analysis of anticipatory lip protrusion across changes in speaking rate.

Susan Shaiman

Graduate Dept. of Speech Pathol., Univ. of Toronto, 6 Queen's Park Crescent West, Toronto, ON M5S 1A8, Canada

Scott G. Adams

The Toronto Hospital, Toronto, ON, Canada

Mikael D. Z. Kimelman

University of Toronto, Toronto, ON, Canada

Studies of coarticulation have attempted to determine when anticipatory activity for an upcoming acoustic segment may be initiated. However, there is only limited information concerning the kinematic characteristics of the lip protrusion gesture itself, particularly across changes in speaking rate. The current study investigated the influence of speaking rate on the shape and symmetry of the upper lip protrusion velocity profile. Five normal speakers demonstrated increased asymmetry of the velocity profile as speaking rate increased or decreased relative to habitual speaking rate. Also, subjects evidenced changes in velocity profile shape and increased numbers of velocity peaks with reduced speaking rates. These results demonstrate that characteristics of the lip protrusion gesture are modified as speaking rate is manipulated. The patterns of change observed in the lip protrusion velocity profiles are comparable to those observed in labial opening and closing gestures, and tongue lowering gestures across speaking rates. These findings suggest that irregularities observed in lip protrusion signals may be related to slow speaking rate, rather than the overlap of articulatory gestures for adjacent phonemes, as has been previously suggested. [Work supported by NSERC.]