Mandible and hyoid bone movements during speech.

Relatively little is known about the extent to which speech-related movements of the mandible and hyoid bone involve rotation and translation. Data were derived from an existing high-speed cineradiograph of 27 disyllables produced by a single adult male speaker of English to address this issue. Time histories of relative locations of both bony components of the mandibular system, expressed in terms equivalent to the sagittal-plane coordinates of two landmarks on each, were analyzed to determine (a) their respective ranges of position and orientation, (b) associations between selected segmental and suprasegmental variables, and subregions of those ranges, and (c) interdependencies between articulator rotation and landmark displacement. In general, data from this speaker, for the mandible and hyoid bone, are consistent with previous reports for the mandible alone, all of which suggest that rotational and translational components of their motions are sufficiently independent to warrant kinematic descriptions that treat both structures as rigid bodies moving in a plane.