The dynamics and control of the tongue during speech

It is well known that humans have to control the motion of their tongue in order to speak intelligibly. However, little is known about the dynamics and control of the tongue. The tongue is unusual in that it does not contain any rigid skeleton. Its movement, which can be very complex, results from the interplay between contracting muscles and the constant volume of the overall structure. A realistic dynamical model of the tongue must be based on a partial differential equation satisfying the constraint of constant volume. Recent advances in imaging technology, ultrasound and tagged cine-MRI (tMRI), have made it possible to obtain good moving images of the tongue surface and its interior points during normal speech. This data makes it possible to test the dynamical model of the tongue proposed in the paper. This model attempts only to describe the behavior of the tongue in the sagittal plane and is linear for simplicity. Ultimately the model will be extended to three dimensions and elaborated to include the essential nonlinearities