Dynamic Analog Speech Synthesizer
George Rosen · The Journal of the Acoustical Society of America · 1958
A dynamically controllable electrical analog of the vocal tract capable of synthesizing sequences of speech sounds is described. The acoustic transmission line between the glottis and lips in the human vocal tract is realized electrically by eleven electronically controlled variable LC sections plus three fixed sections. Each variable capacitor is realized by means of the Miller effect, and the inductors are saturable reactors. Both elements of each section are controlled by a single voltage in a manner that constrains the LC product to remain constant, and varies the ratio L/C to simulate changes in effective cross-sectional area. The analog can be excited by a buzz source to simulate the glottal tone, by a noise source inserted at various distances from the glottis to simulate the noise of turbulence, or by both together. Thus, vowels and most consonants can be produced with equal facility by the dynamic analog. Control voltages are derived from a resistance network in which a series of desired articulatory configurations is stored. A timing arrangement chooses the excitation and articulatory configurations in the proper sequence, and smoothing circuits are used to assure natural transitions from one configuration to the next.