Vocodeur — Wikipedia
The vocoder or vocoder is an electronic sound signal processing device. His name, contraction of voice coder (“Voice Coder” in English), was francized in “vocoder”. He analyzes the main spectral components of the voice (or another sound) and makes a synthetic sound from the result of this analysis.
The vocoder was invented in 1939 by Homer Dudley, engineer at Bell laboratories, in order to ensure effective transmission of voice on the telephone network. Then developed under the name of voder ( Voice Operating DEmonstratoR ), it was presented at the New York Universal Exhibition the same year. An improved version followed in 1940, the vocoder . At first glance, the vocoder was very successful, because it gave the voice a rather robotic texture. However, it was used by the American army in the first Sigsaly digital communication system which notably allowed Franklin Roosevelt and Winston Churchill to communicate beyond the Ocean during the Second World War. In 1945, it was reported by Vannevar Bush in a famous article of As we may think which introduced the notion of World Wide Web (Same). In 1948, he demonstrated it to WDR studios for Werner Meyer-Eppler, director of the Phonetics Institute at Bonn University. The latter was fascinated by the vocal synthesizer and used this first vocoder as a basis for his writings which quickly became the Bible of the German movement of Electronic Musik . Thus the vocoder was ready to be adopted as an instrument.
Dudley’s vocoder cut the voice into 12 frequency bands from which he measured the amplitude. These are the coefficients that were sent to the telephone cable. On the other side by summoning the 12 weighted frequencies of the figures measured, we obtained something similar to the initial message. This process saves almost 90% of the bandwidth. Indeed, the audio signal associated with the voice extends over the frequencies of 400 to 3,400 Hz , or a bandwidth of 3,000 Hz . By breaking down its spectrum into a dozen sub-sets of differently less wide different intensity, you can only use 300 Hz total band width.
The original “Voicecoder” technique is always used in music with certain standardized terms. Two signals, the carrier and the modulator, passed through a Banking Banking Bande-Bande. The amplitude of the modulator is measured via An “envelope follower”. The two signals are then modulated (multiplied) so that the envelope measured on the modulator is applied to the carrier. In this way, the amplitude characteristics of a voice can be applied to a synthesizer sound via a parallel circuit of (band pass)*(amplitude band+follower).
The more this circuit is reproduced in parallel, the more the resynthesis of the modulator (the voice commonly) will be precise. The vocoding technique can also be called “crossed synthesis”.
Some vocoders also make it possible to move the frequencies of signal formants, so that the voice becomes completely distorted and unrecognizable. This technique is used for example to make a speaker on television anonymous.
However, vocoder and please (super Vocoder Phasey/Tukey) should not be confused, which does not at all use the BP filter bank crossing technique, but other complex samples analysis techniques based on the FFT.
After the 1940s, the vocoder had little applications: only certain studios like those of the BBC used them to offer special sounds.
But it was the musicians of the 1970s who will appropriate it, thanks in particular to the British manufacturer of EMS synthesizers who made vocoders with reasonable dimensions and prices. Among them, Kraftwerk, whose practically all compositions from 1973 are embellished with vocoded voice, but also The Buggles, Herbie Hancock, Wendy Carlos, Alan Parsons Project ( The Raven ), Giorgio Moroder, Mike Oldfield, Telex, Tangerine Dream, Frank Zappa, Electric Light Orchestra, Midnight Star, Cynic, Afrika Bambaataa, Laurie Anderson (spécialement le titre O Superman ), or Joe Zawinul. Neil Young will significantly surprise his fans by taking out at the dawn of the 1980s an unusual album, Trans, where half of the titles are sung through a vocoder. The synthetic music composer Jean-Michel Jarre also uses this device on many albums, including the one released in 1988, Revolutions . Frank Farian produced with the famous Vocoder of Sennheiser (25,000 DM at the time) the Boney M. groups then billion Vanilli. Emerson, Lake & Palmer also uses the room Karn Evil 9: Third Impression of album Brain Salad Surgery .
More recently, in the late 1990s and in the 2000s, the vocoder resumed popularity thanks to certain compositions of Eiffel 65, Madonna, Daft Punk, Air, Marboss, Cascada, Booba, etc.
The singer Roger Troutman of the Funk Zapp group, just like Matthias Jabs of Scorpions, Joe Walsh ( Rocky Mountain Way ), Stevie Wonder, Peter Frampton, or Jack White used the talkbox, a device very different from the vocoder – and yet often assimilated wrongly – which makes it possible to modulate a guitar sound or any other instrument with the mouth, through A tube starting from the instrument to the musician’s mouth. David Gilmour, guitarist of the Pink Floyd group, uses the talkbox on the pieces Sheep And Pigs Album animals, then on A New Machine (Part 1) And A New Machine (Part 2) on A Momimentary Lapse of Reason, and finally on the Keep Talking room on The Division Bell.
The vocoder [ first ] Nor should not be confused with the auto-tune (used by musicians as a T-Pain for example), which is a digital device for the correction of the false notes of the voice and which can notably distort the voice until the Completely transform when extreme settings are applied.
Finally, voice synthesis devices, such as votrax designed in the 1970s and also used by Kraftwerk in addition to the vocoder, make it possible to create robotic voices very close or equivalent to those that a vocoder can produce. The electronic educational game console The magic dictation contains a vocal synthetic module of this type.
The vocoder is currently known more as an instrument (or effect) of musical and sound creation than as a means of communication.
- « Vocoder », Encyclopedia of Sciences and Techniques , tome X , Presses de la Cité, 1973.
Related articles [ modifier | Modifier and code ]
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