An Electrical Analog of the Vocal Tract
Κ. Ν. Stevens, S. Kasowski, C. Gunnar M. Fant · The Journal of the Acoustical Society of America · 1953
The design and construction of an electrical analog of the human vocal tract is described. The vocal tract is viewed as an acoustic tube of varying cross-sectional area, terminated by the vocal cords at one end and by the lip opening at the other. The analog is a lumped-constant electrical transmission line consisting of thirty-five pi-sections. Each section represents a 12-cm length of the vocal tract and is adjustable to simulate a range of cross-sectional areas from 0.17 to 17 cm2. The electrical line can be excited by a periodic current source representing the vocal cord output or by a random voltage representing the noise from turbulent air flow at a constriction. The electrical analog can synthesize with good quality all English vowels and some consonants. The physical characteristics of the output of the analog for each sound are shown in terms of measured formant frequencies or by conventional spectrograms. For each sound, the vocal tract dimensions that the electrical network simulates are shown in graphical form. Applications of the speech synthesizer to linguistic and engineering research are discussed briefly.