Determination of the Shape of the Human Vocal Tract from Acoustical Measurements

Abstract

In this paper we describe methods for determining the cross-sectional area function of the human vocal tract from acoustical measurements made at one end. The pressure and volume velocity are assumed to obey Webster's horn equation, which is valid for frequencies below 3.5 kHz. Acoustical properties below 3.5 kHz do not uniquely specify the area function. This paper shows how high frequency information may be incorporated into the mathematical model in a manner consistent with a priori information about the vocal tract. Some results of application of the methods by computer simulation are presented. It is interesting to see from the figures that nine numbers (namely, length, four formants, and four residues) specify the area function quite well for practical purposes.