Article Morphological Variation in the Adult Hard Palate and

Purpose: Adult human vocal tracts display considerable morphological variation across individuals, but the nature and extent of this variation has not been extensively studied for many vocal tract structures. There exists a need to analyze morphological variation and, even more basically, to develop a methodology for morphological analysis of the vocal tract. Such analysis will facilitate fundamental characterization of the speech production system, with broad implications from modeling to explaining interspeaker variability. Method: A data-driven methodology to automatically analyze theextentandvarietyofmorphological variation isproposedand applied toadiversesubjectpoolof36adults.Analysis is focused ontwokeyaspectsofvocal tractstructure: themidsagittal shape of the hard palate and the posterior pharyngeal wall. Result: Palatal morphology varies widely in its degree of concavity but also in anteriority and sharpness. Pharyngeal wall morphology, by contrast, varies mostly in terms of concavity alone. The distribution of morphological characteristics is complex, and analysis suggests that certain variations may be categorical in nature. Conclusion: Major modes of morphological variation are identified, including their relative magnitude, distribution, and categorical nature. Implications of these findings for speech articulation strategies and speech acoustics are discussed