ARTICULATORY ORGANIZATION OF MANDIBULAR, LABIAL, AND VELAR MOVEMENTS DURING SPEECH

It has been shown that articulator movements during speech are adjuste d along a number of spatiotemporal dimensions. For example, variations in the extent of lip, jaw, or tongue motion are associated with propo rtional changes in the respective articulators' peak velocity. Modific ations in the timing of lip and jaw actions are apparently constrained , exhibiting relative timing covariation. Syllable prominence systemat ically affects some combination of the articulator motion parameters, i.e., extent, speed, and duration. The present investigation is an att empt to extend observations of the spatiotemporal properties of articu lator movement to include the velum. Lip, jaw, and velar kinematics we re recorded optoelectronically and simultaneously with the acoustic si gnal during productions of the utterance /mabnab/. The spatial and tem poral relations between the lips, the jaw, and the velum were examined and compared across articulators. For movements associated with each syllable, the velum displayed scaling patterns qualitatively similar t o those of the lips and jaw. Moreover, velocity-displacement relations were more robust for the lowering than for the raising movements of t he velum. There was evidence of interarticulator coupling between the velum and the jaw, and between the velum and the upper lip, although t his coupling was not as strong as that observed among the oral articul ators. Articulator specific differences in velocity-displacement corre lations and degree of interarticulator cohesion for the various moveme nt phases may be related to a combination of aerodynamic and phonetic factors, such as the phonologically noncontrastive nature of nasalizat ion in English. (C) 1995 Acoustical Society of America.