Relationships between articulatory and acoustic measurements from an x‐ray microbeam study of variability in the production of the vowels /i/ and /a/

Abstract

We have reported previously that midsagittal distributions of points on the dorsal tongue surface for multiple repetitions of the vowels /i/ and /a/ show more variation along a direction parallel to the vocal tract midline than perpendicular to the midline. This finding was interpreted as support for a hypothesis based on articulatory‐to‐acoustic modeling: the programming of movements towards the vowel targets is sensitive to non‐linear relationships between articulatory displacements and formants [J. S. Perkell and W. L. Nelson in Speech Motor Control, edited by S. Grillner, A. Persson, B. Lindblom, and J. Lubker (Pergamon, New York, 1982)]. Statistics on formant values for one subject have been calculated, and pairwise regressions of displacement and formant data have been run. An articulatory synthesizer [P. Rubin, T. Baer, and P. Mermelstein, J. Acoust. Soc. Am. 70, 321–328 (1981)] has been manipulated through displacements similar to the subject's articulatory variation. The range of formant variation for the subject is comparable to the range of formant values produced by the synthesizer. However, there were only very weak correlations between the subject's articulatory displacements and his formant data. Possible reasons for the lack of correlations will be discussed. [Work supported in part by NIH Grant No. NS04332.]