Palate shape effects on characteristic vowel tongue postures
Mark Tiede · The Journal of the Acoustical Society of America · 1998
In this work MRI vocal tract data obtained during sustained vowel production is used to investigate the interaction between individual speaker differences in hard palate shape and the compensatory adjustments to tongue posture needed to tune language-specific vowel formant resonances. PCA techniques developed in previous work [Tiede and Yehia, J. Acoust. Soc. Am. 100, 2658(A) (1996)] were used to characterize three-dimensional tongue and palate shapes for vowel inventories of five Japanese and five American English subjects. Parametrized shapes for individual speakers were compared to a normalized mean tract shape pooled across subjects for each language. Preliminary results show that the axis of tongue body displacement is associated with oral cavity depth (OCD, measured from the teeth to the rear pharyngeal wall): Shorter OCD subjects showed greater vertical /a/ versus /i/ differences, and longer OCD subjects used more of a horizontal component. Systematic effects of palate vault shape on tongue constriction location have also been observed. These results are consistent with the speaker-specific articulatory (‘‘A’’ space) adaptations suggested in previous work [Honda et al., Proc. ICSLP96, 784–787 (1996)].