10.6

321Logic Pro Instruments
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 artificial voice synthesizer, as
follows:
• Parallel bandpass vocoder: A speech analyzer and resynthesizer.
• 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 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.
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 Dudley’s unit, Bob Moog and Wendy Carlos modified a number of
synthesizer modules to create their own vocoder for the Clockwork Orange soundtrack.
Peter Zinovieff’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 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.
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.