Mechanical properties of How to characterize differen

Face deformations during speech in different styles are observed by measuring movements of 65 markers glued on the subject's face including the lips. A factor analysis decomposes lower lip movements generated by jaw gestures and those by intrinsic lip gestures. We then characterize mechanical properties of these movements in terms of global variables calculated over an utterance as the total movement time, distance traveled, average speed, and some variables related to muscular energy expenditure. Both rapid and clear speech require high muscular energy expenditure. The energy requirement in the former is a demand for power to maintain motion speed at a high level, whereas that in the latter is that for force to maintain a high level of accelerations along the utterance.