Motor control similarity between speakers saying "a souk" using inverse atlas tongue modeling.

Finite element models (FEM) of the tongue have facilitated speech studies through analysis of internal muscle forces indirectly derived from imaging data. In this work, we build a uniform hexahedral FEM of a tongue atlas constructed from magnetic resonance imaging data of a healthy population. The FEM is driven by inverse internal tongue tissue kinematics of speakers temporally aligned and deformed into the same atlas space, while performing the speech task "a souk" allowing muscle activation predictions. This work aims to investigate the commonalities in tongue motor strategies in the articulation of "a souk" predicted by the inverse tongue atlas model. Our findings report variability among five speakers for estimated muscle activations with a similarity index using a dynamic time warp function. Two speakers show similarity index > 0.9 and two others < 0.7 with respect to a reference speaker for most tongue muscles. The relative motion tracking error of the model is less than 2% which is promising for speech study applications.