Three-dimensional representation of articulatory kinematics from x-ray microbeam data
John R. Westbury, Qiuzhen Xue · The Journal of the Acoustical Society of America · 1988
Records of speech-related movements of flesh points and anatomic landmarks obtained from the University of Wisconsin x-ray microbeam system are fundamentally two dimensional in the sense that they provide time histories of relative positions of points within a plane. However, the third spatial dimension associated with each point is implicit in its two-space representation and, under special conditions, can be reconstructed mathematically. For example, three points attached to a rigid body such as the mandible determine a system of three polynomial equations, which, when solved, provides an account of the location of each point with respect to sagittal and coronal plane axes. Both the feasibility and resolution limits of a conventional numerical approach to this problem have been established by analysis of calibrated movements of three-point arrays attached to a machine-driven phantom and tracked by the microbeam system. Moreover, the same analysis procedure has been applied to kinematic data for multipoint arrays attached to the head and mandible of nine adult subjects to determine whether and to what extent their respective movements, during speech and other selected oral motor behaviors, are restricted to the sagittal plane. The advantages of a three-dimensional representation of speech motor behavior for at least these structures, within the context of recent microbeam experiments, will be discussed. [Work supported by NIH Grant NS-16373.]