The relationship of vocal tract shape to, three voice qualities

Three-dimensional vocal tract shapes and consequent area functions represen ting the vowels [i, ae, a, u] have been obtained from one male and one fema le speaker using magnetic resonance imaging (MRI). The two speakers were tr ained vocal performers and both were adept at manipulation of vocal tract s hape to alter voice quality. Each vowel was performed three times, each wit h one of the three voice qualities: normal, yawny, and twangy. The purpose of the study was to determine some ways in which the vocal tract shape can be manipulated to alter voice quality while retaining a desired phonetic qu ality. To summarize any overall tract shaping tendencies mean area function s were subsequently computed across the four vowels produced within each sp ecific voice quality. Relative to normal speech, both the vowel area functi ons and mean area functions showed, in general, that the oral cavity is wid ened and tract length increased for the yawny productions. The twangy vowel s were characterized by shortened tract length, widened lip opening, and a slightly constricted oral cavity. The resulting acoustic characteristics of these articulatory alterations consisted of the first two formants (F1 and F2) being close together for all yawny vowels and far apart for all the tw angy vowels. (C) 2001 Acollstical Society of America.