ASA 124th Meeting New Orleans 1992 October

3pSP9. Rigid body reconstruction of jaw motion in speech.

Eric Vatikiotis-Bateson

ATR Auditory and Visual Perception Res. Labs., 2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-02, Japan

David J. Ostry

McGill Univ., Montreal, Canada

Typically, during speech, the jaw rotates downward and translates forward during opening movements and follows the opposite path during closing; however, rotations and translations out of the midsagittal plane may also occur. In this study, Optotrak was used to examine jaw motion in six degrees of freedom---three orientations and three positions---relative to the occlusal (bite) plane and the condyle. Native speakers of English (2) and Japanese (2) produced CVCV(schwa) utterances in normal and fast rate as well as in loud speech conditions. As has been reported previously, the principle components of jaw motion were horizontal translation and rotation in the midsagittal plane. However, rotations out of the midsagittal plane are also observed. Yaw about the longitudinal body axis was typically about 3 deg and roll usually less than 2 deg. Magnitude of yaw and roll angles differed little across conditions. The remaining translational components---vertical and lateral---were small in magnitude and uncorrelated with either sagittal plane rotation or horizontal translation.