Articulatory Analog of the Vocal Tract and Nasal Cavities

A modified version of the dynamically controllable electrical analog of the vocal tract [G. Rosen, J. Acoust. Soc. Am. 30, 201–209 (1958)] that includes a recently developed analog of the nasal cavities is described. The acoustical coupling between the vocal tract and the nasal cavities is electronically varied in the same way as the effective cross-sectional area of each section making up the transmission line representing the vocal tract. Formal listening tests have been conducted to determine the most suitable vocal-tract configurations for the production of nasal consonants in consonant-vowel and vowel-consonant syllables. Other listening tests have determined the most suitable patterns of temporal variables for the production of these syllables. In general, it is found that more natural-sounding syllables are obtained when the velopharyngeal coupling varies slowly with time compared to changes in the configuration of the vocal tract. The results compare favorably with cineradiological data recently reported and are interpreted to support the point of view that studies of the performance of an articulatory synthesizer reveal important details concerning the production and perception of natural speech. The experiments demonstrate that speech can be synthesized from articulatory information in a straightforward and natural manner. (This work was supported in part by the U. S. Army Signal Corps, the Air Force Office of Scientific Research, and the Office of Naval Research; and in part by the Air Force Cambridge Research Laboratories and the National Science Foundation.)