Predicting pharynx shape from the tongue during vowel production

Abstract

The shape of the pharynx greatly affects the formants of vowels, yet the measurement of pharyngeal shape is relatively difficult. Using midsagittal MRI images of a male speaker producing eleven English vowels, the predictability of pharyngeal shape during vowel production was assessed. There were two categories of predictors: measured and categorical. Measured predictors were four points on the tongue representing the points likely to be locations for receiver coils in an electromagnetometer system. Categorical predictors were vowel frontness and height, and the typical position of the epiglottis relative to the base of the tongue (as seen in MRI images). Midsagittal distance was measured at 3-mm intervals along the vocal tract length. A stepwise regression using measured and categorical variables gave good predictions for all distances along the vocal tract (r greater than 0.80), except near the uvula. (Using just the categorical predictors resulted in surprisingly good estimations.) Position of the uvula varied across repetitions of the vowels, and so exclusion of the uvula increased predictability in the uvular region. For static vowel patterns in English, then, pharynx shape is fairly predictable from tongue shape. [Supported by NIH grant DC-02717.]