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Chapter 8 EVOC 20 PolySynth 152
Vocoder history
The development of the vocoder dates back to the 1930s in the telecommunications industry.
Homer Dudley, a research physicist at Bell Laboratories in New Jersey, developed the vocoder
(short for voice encoder) as a research machine. It was originally designed to test compression
schemes for the secure transmission of voice signals over copper phone lines.
It was a composite device consisting of an analyzer and an articial voice synthesizer, as follows:
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Parallel bandpass vocoder: A speech analyzer and resynthesizer.
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Vocoder speech synthesizer: A voice modeler, this valve-driven machine was played by a human
operator. It had two keyboards, buttons to recreate consonants, a pedal for oscillator frequency
control, and a wrist-bar to switch vowel sounds on and o.
The analyzer detected the energy levels of successive sound samples, measured over the entire
audio frequency spectrum via a series of narrow band lters. The results of this analysis could be
viewed graphically as functions of frequency against time.
The synthesizer reversed the process by scanning the data from the analyzer and supplying
the results to a number of analytical lters, hooked up to a noise generator. This combination
produced sounds.
In World War II, the vocoder (known then as the voice encoder) proved to be of crucial
importance, scrambling the transoceanic conversations between Winston Churchill and Franklin
Delano Roosevelt.
Werner Meyer-Eppler, the director of Phonetics at Bonn University, recognized the relevance of
the machines to electronic music—following a visit by Dudley in 1948. Meyer-Eppler used the
vocoder as a basis for his future writings which, in turn, became the inspiration for the German
“Elektronische Musik” movement.
In the 1950s, a handful of recordings ensued.
In 1960, the Siemens Synthesizer was developed in Munich. Among its many oscillators and
lters, it included a valve-based vocoding circuit.
In 1967, a company called Sylvania created a number of digital machines that used time-based
analysis of input signals, rather than bandpass lter analysis.
In 1971, after studying Dudley’s unit, Bob Moog and Wendy Carlos modied a number of
synthesizer modules to create their own vocoder for the Clockwork Orange soundtrack.
Peter Zinovie’s London-based company EMS developed a standalone—and altogether more
portable—vocoder. EMS is probably best known for the Synthi AKS and VCS3 synthesizers. The
EMS Studio Vocoder was the world’s rst commercially available machine, released in 1976. It was
later renamed the EMS 5000. Among its users were Stevie Wonder and Kraftwerk. Stockhausen,
the German “Elektronische Musik” pioneer, also used an EMS vocoder.
Sennheiser released the VMS 201 in 1977, and EMS released the EMS 2000, which was a cut-down
version of its older sibling.
1978 saw the beginning of mainstream vocoder use, riding on the back of popularity created
through the music of Herbie Hancock, Kraftwerk, and a handful of other artists. Among the
manufacturers who jumped into vocoder production at this time are Synton/Bode, Electro-
Harmonix, and Korg, with the VC-10.