Articulatory organization of mandibular, labial, and velar movements during speech.

It has been shown that articulator movements during speech are adjusted along a number of spatiotemporal dimensions. For example, variations in the extent of lip, jaw, or tongue motion are associated with proportional changes in the respective articulators' peak velocity. Modifications in the timing of lip and jaw actions are apparently constrained, exhibiting relative timing covariation. Syllable prominence systematically affects some combination of the articular motion parameters, i.e., extent, speed, and duration. The present investigation is an attempt to extend observations of the spatiotemporal properties of articulator movement to include the velum. Lip, jaw, and velar kinematics were recorded optoelectronically and simultaneously with the acoustic signal during productions of the utterance/mabnab/. The spatial and temporal 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 pattern qualitatively similar to those of the lips and jaw. Moreover, velocity-displacement relations were more robust for the lowering than for the raising movements of the velum. There was evidence of interarticulator coupling between the velum and the jaw, and between the velum and the upper lip, although this coupling was not as strong as that observed among the oral articulators. Articulator specific differences in velocity-displacement correlations and degree of interarticulator cohesion for the various movement phases may be related to a combination of aerodynamic and phonetic factors, such as the phonologically noncontrastive nature of nasalization in English.