Yuki Kakita

Physiology of the lips and modelingof lip gestures

Abstract The lips are one of the articulators for producing speech sounds, and also contribute to the generation of phonetic information to be visually perceived by the listeners. For this reason, lip gestures for speech provide a useful research topic for investigating multimodal aspects of speech production and perception. As a device for studying these issues, a computational model has been developed to represent the time-varying lip contour controlled by the contraction pattern of labial musculature. Data from simultaneous measurements of lip contour shapes and perioral muscle EMG have been analyzed to build a model of lip contour in the frontal view. The modeling principle is a linear mapping from muscle contraction pattern to lip contour deformation. A multiple linear regression analysis is employed to estimate each x- and y-coordinate for seven measured points on the lip contour from the integrated EMG signals. The analysis of EMG signals indicates a pattern of muscle group selection for typical lip gestures. The orbicularis oris inferior (OOI) and the depressor labii inferior (DLI) co-contract for lip rounding. The peripheral layer of the OOI shows an increased activity for lip protrusion. The model as well as the preliminary data appear promising for our research goal of understanding the organization of speech production and perception.