Tongue Contour Reconstruction from Optical and Electrical Palatography

Tongue shape reconstruction based on safe and convenient measurement techniques is of great interest for speech research and speech therapy. Two potentially useful and related measurement techniques for this purpose are electropalatography (EPG) and optopalatography (OPG). While EPG measures the time-varying contact pattern between the hard palate and the tongue, OPG measures distances between the two. Here, we examined the potential of EPG, OPG, and their combination for predicting the whole tongue contour using a multiple linear regression model. The model was trained and tested with tongue shapes and virtual sensor data obtained from Magnetic Resonance Images of sustained articulations of two speakers. When the model was trained and tested with the same speaker, the error of tongue contour reconstruction was significantly lower for predictions based on OPG data than for predictions based on EPG data. When the model was trained with one speaker and tested with the other, the error pattern was less consistent and the overall error was higher. Hence, especially OPG is well suited for tongue contour prediction, but an adaptation method is needed to transfer the model to a new speaker.