An experimental study of acoustic characteristics of hypopharyngeal cavities using vocal tract solid models

Abstract

Solid models of the vocal tract with hypopharyngeal cavities were molded with a stereolithographic technique based on MRI data obtained from a male speaker during the production of Japanese vowels /a/ and /o/. A vowel synthesis experiment conducted with the models revealed a relatively good agreement in the second and third formants, as well as in anti-resonance at 4-5 kHz. The elimination of the models' piriform fossa resulted in the disappearance of the anti-resonance and shifts of the adjacent formants. The modification of the laryngeal cavity into a uniform tube caused spectral changes in the frequency range of 1.5-7.0 kHz. These acoustic effects of hypopharyngeal cavities were dependent on vocal tract shapes.