Speaker-specific biomechanical models: From acoustic variability via articulatory variability to the variability of motor commands in selected tongue mucles

In this work we have constructed biomechanical tongue models derived from MRI data in order to investigate the effects of differing locations of vocal tract bending on variability in motor command space and overall articulatory variability for vowel targets. Acoustic models predict negligible effects of the bend of the vocal tract if its length is held constant. However, the location of this bend crucially determines the relation between vertical and horizontal dimensions of the tract and thus the relative freedom of tongue movement within these dimensions. We predict that articulatory variability will be greater along those dimensions with more degrees of freedom as determined by vocal tract configuration imposed by bend location, and present simulation results that in general support this position.