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The Voder (1939)

"Probably the first electrical synthesizer which attempted to produce connected speech was the Voder (Dudley, Riesz and Watkins). It was basically a spectrum-synthesis device operated from a finger keyboard. It did, however, duplicate one important physiological characteristic of the vocal system, namely, that the excitation can be voiced or unvoiced. A schematic diagram of the device is shown below."


Schematic diagram of the Voder synthesizer

"The 'resonance control' box of the device contains 10 contiguous band-pass filters which span the speech frequency range and are connected in parallel. All the filters receive excitation from either the noise source or the buzz (relaxation) oscillator. The wrist bar selects the excitation source, and a foot pedal controls the pitch of the buzz oscillator. The outputs of the band-pass filters pass through potentiometer gain controls and are added. Ten fingerkeys operate the potentiometers. Three additional keys provide a transient excitation of selected filters to simulate stop-consonant sounds."

"This speaking machine was demonstrated by trained operators at the World's Fairs of 1939 (New York) and 1940 (San Francisco). Although the training required was quite long (on the order of a year or more), the operators were able to 'play' the machines -- literally as though they were organs or pianos -- and to produce intelligible speech. (Note: H. W. Dudley retired from the Bell Laboratories in October 1961. On the completion of his more than 40 years in speech research, one of the Voder machines was retrieved from storage and refurbished. In addition, one of the original operators was invited to return and perform for the occasion. Amazingly, after an interlude of twenty years, the lady was able to sit down to the console and make the machine speak.) More recently, further research studies based upon the Voder principle have been carried out (Oizumi and Kubo)."

James L. Flanagan, "Speech Analysis, Synthesis and Perception", Springer-Verlag, 1965, pp. 172-173.

Listen to the voder (AIFF, 381K).