Characterization of tongue shape.

Mathematical techniques are described for analyzing tongue shapes obtained with ultrasound images. The surface of the mid-sagittal section of the tongue was approximated by discrete points. In turn, these points were used to approximate position, slope and curvature of the tongue surface at a fixed time during speech. Two approaches were employed. The first method involved the use of finite difference approximations to derivatives of the function of tongue position. The second utilized a curve fit. Both methods were examined for reliability. Results of these analyses on a simple, single speech sound are discussed.