2aSC2. Across session variability in lip--jaw synergies for bilabial closure.

Session: Tuesday Morning, May 14

Time: 8:45

Author: Peter J. Alfonso
Location: Dept. of Speech and Hearing Sci., Univ. of Illinois, 901 S. Sixth St., Champaign, IL 61820


Movements of the tongue, lips, and jaw were transduced by electromagnetic midsagittal articulography. A single session included 20 repetitions of /pap/,/tat/, and /sas/ imbedded in a carrier phase at normal, slow, and fast speech rates. Seven talkers completed three sessions at 1-week intervals. Reported here are across-session comparisons of lip--jaw displacements, velocities, temporal ordering, and relative timing for bilabial closure at normal rates. Four of the seven subjects showed stable but idiosyncratic spatial and temporal organizational characteristics within and across sessions. Subjects who are relatively unstable across sessions in regard to displacement characteristics are also relatively unstable in regard to temporal ordering and relative time. Only motor equivalence covariability is stable across sessions for all subjects, that is, even in the case of unstable spatial and temporal organizational characteristics. Results seem to support a task-dynamic point of view, namely, that the spatial and temporal organizational characteristics of the individual articulators that comprise an articulatory complex represent the natural consequence of gestural coordination (inferred here by motor equivalence index) and therefore would not demonstrate stability across sections. [Work supported by NIH DC-00121 to Haskins Laboratories and University of Illinois research grant.]

from ASA 131st Meeting, Indianapolis, May 1996