A model of vocal-tract acoustics and aeroacoustics validated by flow experiments
Philip J. B. Jackson, Christine H. Shadle · The Journal of the Acoustical Society of America · 1999
Modeling the acoustic response of the vocal tract is a complex task, both from the point of view of acquiring details of its internal geometry and of accounting for the acoustic-flow interactions. A vocal-tract acoustics program (VOAC) has been developed [P. Davies, R. McGowan, and C. Shadle, in Vocal Fold Physics, edited by I. Titze (Singular, San Diego, 1993), pp. 93–142], which uses a more realistic, aeroacoustic model of the vocal tract than classic electrical-analog representations. It accommodates area and hydraulic radius profiles, smooth and abrupt area changes, incorporating end corrections, side branches, and net fluid flows, including turbulence losses incurred through jet formation. Originally, VOAC was tested by comparing vowel formant frequencies (i) uttered by subjects, (ii) predicted using classic electrical analog, and (iii) predicted by VOAC. In this study, VOAC is further validated by comparing the predicted frequency response functions for a range of flow rates with measurements of the radiated sound from a series of mechanical models of unvoiced fricatives [C. Shadle, Ph.D. thesis, MIT-RLE Tech. Report 506 (1985)]. Results show VOAC is more accurate in predicting the complete spectrum at a range of flow rates. Finally, preliminary work is presented with VOAC used to simulate the sound generated at a sequence of stages during the release of a plosive.