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Table Of Contents
Vocoder speech synthesizer: A voice modeler, invented in 1939. 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
off.
The analyzer detected the energy levels of successive sound samples, measured over the
entire audio frequency spectrum via a series of narrow band filters. 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 filters, hooked up to a noise generator. This
combination produced sounds.
The Voder was demonstrated at the 1939 World Fair, where it caused quite a stir. 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 filters, 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 filter analysis.
In 1971, after studying Dudleys unit, Bob Moog and Wendy Carlos modified a number
of synthesizer modules to create their own vocoder for the Clockwork Orange sound track.
Peter Zinovieffs 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 first 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.
159Chapter 7 EVOC 20 PolySynth