Using acoustic data to improve estimates of the mapping from saggital dimensions to area functions

Abstract

Formant frequency data was used to adjust estimates of 18 cross-sectional areas of the vocal tract produced by a conversion function relating midsaggital dimensions in lateral x rays to direct physiological measurements of vocal tract area [P. Ladefoged, J. Anthony, and C. Riley, UCLA Working Papers in Phonetics 19, 4–13 (1971)]. The logarithm of the estimated area function was described by Fourier coefficients and bandlimited by preserving 2n components. The odd-numbered Fourier coefficients were adjusted until a match was achieved between the measured formant frequencies and the admittance poles for the estimated area function. The even coefficients retained their original values thereby providing a unique determination of the area function constrained by the original estimate of tract shape. Fifty sets of estimates based on the midsaggital dimensions of ten American English vowels spoken by five speakers, and their corresponding formant frequencies, aided in the construction of an improved conversion function mapping midsaggital distances to cross-sectional areas for the vocal tract. [Work supported by NIH.]