The Birth Of The Vocoder And It’s Use In Modern Music (With Audio Examples)

Homer Dudley‘s Speech Synthesisers, “The Vocoder” (1940) & “Voder”(1939)



The Siemens system was used by many European experimental composers throughout the 50’s and 60’s including Mauricio Kagel, Bengt Hambreus, Milko Kelemen and the director of the Munich Studio Für Elektronische Musik, Josef Anton Riedl.


A vocoder (pronounced /ˈvoʊkoʊdər/, a combination of the words voice and encoder) is an analysis / synthesis system, mostly used for speech. In the encoder, the input is passed through a multiband filter, each band is passed through an envelope follower, and the control signals from the envelope followers are communicated to the decoder. The decoder applies these (amplitude) control signals to corresponding filters in the (re) synthesizer.

It was originally developed as a speech coder for telecommunications applications in the 1930s, the idea being to code speech for transmission. Its primary use in this fashion is for secure radio communication, where voice has to be encrypted and then transmitted. The advantage of this method of “encryption” is that no ‘signal’ is sent, but rather envelopes of the bandpass filters. The receiving unit needs to be set up in the same channel configuration to resynthesize a version of the original signal spectrum. The vocoder as both hardware and software has also been used extensively as an electronic musical instrument.

“At the 1939 World’s Fair a machine called a Voder was shown . A girl stroked its keys and it emitted recognsable speech. No human vocal cords entered into the procedure at any point; the keys simply combined some electronically produced vibrations and passed these on to a loud-speaker.”
(“As We May Think” by Vannevar Bush, 1945. )

YouTube Vocoder Video

From: The Dance Music Manual by Rick Snoman :

One final effect that’s particularly useful if the vocalist is incapable of singing in key is the vocoder. Of all the vocal effects, these are not only the most instantly recognizable, but are also the most susceptible to changes in fashion. The robotic voices and talking synth effects they generate can be incredibly clichéd unless they’re used both carefully and creatively, but the way in which they operate opens up a whole host of creative opportunities. Fundamentally, vocoders are simple in design and allow you to use one sound – usually your voice (known as the modulator) – to control the tonal characteristics of a second sound (known as the carrier), which is usually a synthesizer’s sustained timbre. However, as simple as this may initially appear, actually producing musically usable results is a little more difficult, since simply dialling up a synth preset and talking, or singing, over it will more often than not produce unusable results. Indeed, to use a vocoder in a musically useful way, it’s important to have a good understanding of exactly how they work and to do this we need to begin by examining human speech. A vocoder works on the principle that we can divide the human voice into a number of distinct frequency bands. For instance, plosive sounds such as ‘p’ or ‘b’ consist mostly of low frequencies, ‘s’ or ‘t’ sounds consist mostly of high frequencies, vowels consist mostly of mid-range frequencies and so forth. When a vocal signal enters the vocoder, a spectral analyser measures the signal’s properties and subsequently uses a number of filters to divide the signal into a number of different frequency bands. Once divided, each frequency band is sent to an envelope follower, which produces a series of control voltages3 based on the frequency content and volume of the vocal part. This exact same principle is also used on the carrier signal and these are tuned to the same frequency bands as the modulator’s input. However, rather than generate a series of control voltages, they are connected to a series of voltage-controlled amplifiers. Thus, as you speak into the microphone the subsequent frequencies and volume act upon the carrier’s voltage-controlled amplifiers, which either attenuates or amplifies the carrier signal, in effect superimposing your voice onto the instrument’s timbre. Consequently, since the vocoder analyses the spectral content and not the pitch of the modulator, it isn’t necessary to sing in tune as it wouldn’t make any difference. From this, we can also determine that the more filters that are contained in the vocoder’s bank, the more accurately it will be able to analyse and divide the modulating signal, and if this happens to be a voice, it will be much more comprehensible.  Typically, a vocoder should have a minimum of six frequency bands to make speech understandable, but it’s important to note that the number of bands available isn’t the only factor when using a vocoder on vocals. The intelligibility of natural speech is centred between 2.5 and 5 kHz; higher or lower than this and we find it difficult to determine what’s being said. This means that when using a vocoder, the carrier signal must be rich in harmonics around these frequencies, since if it’s any higher or lower then some frequencies of speech may be missed altogether. To prevent this, it’s prudent to use a couple of shelving filters to remove all frequencies below 2 kHz and above 5 kHz before feeding them into the vocoder. Similarly, for best results the carrier signal’s sustain portion should remain fairly constant to help maintain some intelligibility. For instance, if the sustain portion is subject to an LFO modulating the pitch or filter, the frequency content will be subject to a cyclic change that may push it in and out of the boundaries of speech, resulting in some words being comprehensible while others become unintelligible.  Plus, it should also go without saying that if you plan on using your voice to act as a modulator it’s essential that what you have to say, or sing, is intelligible in the first place. This means you should ensure that all the words are pronounced coherently and clearly.  More importantly, vocal tracks will unquestionably change in amplitude throughout the phrases and this will create huge differences in the control voltages generated by the vocoder.  This results in the VCA levels that are imposed onto the carrier signal to follow this change in level producing an uneven vocoded effect, which can distort the results. Subsequently, it’s an idea to compress the vocals before they enter the vocoder and if the carrier wave uses an LFO to modulate the volume compress this too.  The settings to use will depend entirely on the vocals themselves and the impact you want them to have in the mix (bear in mind that dynamics can affect the emotional impact), but as a very general starting point set the ratio on both carrier and modulator to 3:1 with a fast attack and release, and then reduce the threshold so that the quietest parts only just register on the gain reduction meter. Additionally, remember that it isn’t just vocals that will trigger the vocoder and breath noises, rumble from the microphone stand and any extraneous background noises will also trigger it.  Thus, along with a compressor you should also consider employing a noise gate to remove the possibility of any superfluous noises being introduced. With both carrier and modulator under control there’s a much better chance of producing a musically useful effect and the first stop for any vocoder is to recreate the robotic voice.  To produce this effect, the vocoder needs to be used as an insert effect, not send, as all of the vocal line should go through the vocoder. Once this modulator is entering the vocoder you’ll need to program a suitable carrier wave. Obviously, it’s the tone of this carrier wave that will produce the overall effect, and two sawtooth waves detuned from each other by _ and _4 with a short attack, decay and release but a very long sustain should provide the required timbre. If, however, this makes the vocals appear a little too bright, sharp, thin or ‘edgy’ it may be worthwhile replacing one of the sawtooth waves with a square or sine wave to add some bottom-end weight. Though this effect is undoubtedly great fun for the first couple of minutes, after the typical Luke, I am your father’ it can wear thin and if used as is in a dance track it will probably sound a little too clichéd, so it’s worthwhile experimenting further.  Unsurprisingly, much of the experimentation with a vocoder comes from modulating the carrier wave in one way or another and the simplest place to start is by adjusting the pitch in time with the vocals. This can be accomplished easily in any audio/MIDI sequencer by programming a series of MIDI notes to play out to the carrier synth, in effect creating a vocal melody. Similarly, an arpeggio sequence used as a carrier wave can create a strange gated, pitch-shifting effect, while an LFO modulating the pitch can create an unusual cyclic pitch-shifted vocal effect. Filter cut-off and resonance can also impart an interesting effect on vocals and in many sequencers this can be automated so that it slowly opens during the verses, creating a build-up to a chorus section. Also, note that the carrier does not necessarily have to be created with saw waves, and a sine wave played around C3 or C4 can be used to recreate a more tonally natural vocal melody that will have some peculiarity surrounding it. Note: Vocoders do not always have to be used on vocals and you can produce great results by using them to impose one instrument onto another. For instance, using a drum loop as a modulator and a pad as the carrier, the pad will create a gating effect between the kicks of the loop. Alternatively, using the pad as a modulator and the drums as the carrier wave, the drum loops will turn into a loop created by a pad! Ultimately these have only been simple suggestions to point you in a more creative direction and you should be willing to try out any effects you can lay your hands on to hear the effect it can have on a vocal. Bear in mind that due to the very nature of dance music it’s always open to experimentation and it’s much better to initiate a new trend than simply follow one set by another artist.

Vocoder Sound Files:

Pauline Oliveros

Alvin Lucier

John Cage

Robert Ashley

Toshi Ichyangi

Morton Feldman

Morton Feldman

Herbert Eimert What is Electronic Music – Die Reihe Vol1 1957

Herbert Eimert (April 8, 1897, Bad Kreuznach, Germany – Decembre 15, 1972, Düsseldorf, Germany) was a composer and a musicologist who studied at the Music Conservatory of Cologne and at Cologne University. He worked as a journalist and joined the station as a music editor and programmer. Together with sound engineer colleague Robert Beyer, he succeeded in founding the famous electronic studio in 1951. From 1953, Eimert invited Karlheinz Stockhausen & Gottfried Michael Koenig to work in the studio he directed until 1962.

Sun Ra: Space is the Place (1974)


Sun Ra: Space is the Place (1974)

Sun Ra Official Page (Page Opens With Music)

From Wiki:

“Sun Ra (birth name: Herman Poole Blount, legal name Le Sony’r Ra; (b. May 22, 1914 – May 30, 1993) was born in Birmingham, Alabama. He was a prolific jazz composer, bandleader, piano and synthesizer player, poet and philosopher known for his “cosmic philosophy,” musical compositions and performances.”

Press Here For Interview Of Sun Ra


Karlheinz Essl: Lexikon-Sonate – Algorithmic Music Generator

Karlheinz Essl: Lexikon-Sonate – algorithmic music generator.

One of many Mac software applications on this great music site.



Reason CV to Moogerfoogers

Press Here For Reason To CV

This may be something to try for anyone who wants to experiment with software-to-CV conversion.  In this case you will be going from Reason to a Moogerfooger.  I’ve never used or seen MOTU Volta but this is worth a try.

From Wiki:

CV/Gate (an abbreviation of Control Voltage/Gate) is an analog method of controlling synthesizers, drum machines and other similar equipment with external sequencers. The Control Voltage typically controls pitch and the Gate signal controls note on/off.

This method was widely used in the epoch of analog modular synthesizers, beginning in the 1960s and up to the early 1980s.[1][2] It was mostly superseded by the MIDI protocol, which is more feature-rich, easier to configure reliably, and more easily supports polyphony.[3] Also, the advent of digital synthesizers, like the 1977 Prophet-5 and 1983 Yamaha DX-7, made it possible to store and retrieve voice ‘patches’ – eliminating patch cables[4] and (for the most part) control voltages.[5]Contents [hide]
1 Basic usage
1.1 CV
1.2 Gate
2 Modern usage
3 References
4 See also
5 External links

Basic usage

As early analog synths were modular, each synthesizer component (e.g. LFO, VCF) could be connected to another component by means of a patch cable that transmits voltage, with changes in that voltage causing changes to one or more parameters of the component. The most popular example of this technique is a keyboard that transmits a signal with two components:
CV (Control Voltage) indicates which note (event) to play: a different voltage for each key pressed; those voltages are typically connected to one or more oscillators, thus producing the different pitches required. Note that such a method implies that the synthesizer is monophonic.
Gate (sometimes called Trigger) indicates when a note should start, a pulse that is used to trigger an event, typically an ADSR envelope. In the case of triggering a drum machine, a clock signal or LFO square wave could be employed to signal the next beat (or rest).

While the concept of CV (Control Voltage) was fairly standard on analog synths, the implementation was not. For pitch control via CV, there are two prominent implementations:
Volts per octave. This standard was popularized by Bob Moog, if not created, in the 1960s; it was widely adopted for control interfacing.One volt represents one octave, so the pitch produced by a voltage of 3 V would be one octave lower than that produced by a voltage of 4 V. Notable followers of this standard include Roland, Moog, Sequential Circuits, Oberheim and ARP.
Hertz per volt. This method (used by Korg and Yamaha synths) represented an octave of pitch by doubling voltage, so the pitch represented by 2 V would be one octave lower than that represented by 4 V, and one higher than that represented by 1 V.

The following example table demonstrates some notes and their corresponding voltage levels in both implementations (this example uses 1 V/octave and 55 Hz/V):Note A1 A2 A3 B3 C4 D4 E4 A4 A5
Volts per octave scheme, V 1.000 2.000 3.000 3.167 3.250 3.417 3.583 4.000 5.000
Frequency, Hz 55 110 220 247 261 294 330 440 880
Hertz per volt, V 1.000 2.000 4.000 4.491 4.745 5.345 6.000 8.000 16.000

Generally, these two implementations are not critically incompatible; voltage levels used are comparable and there are no other safety mechanisms. So, for example, using a Hz/Volt keyboard to control a Volts/Octave synthesizer would eventually produce some sound, but it will be terribly out of tune. Commercial solutions are available to get round this problem, most notably the Korg MS-02 CV/trigger interface.

On synthesizers, this signal is usually labelled as “CV”, “VCO In”, “Keyboard In”, “OSC” or “Keyboard Voltage”.

Gate (Trigger) also has two implementations:
V-Trigger (“voltage trigger”, sometimes called “positive trigger”). This method involves keeping normally low voltage (around 0V) on trigger and producing a fixed positive voltage to indicate a note is on. The amount of voltage required differs from synth to synth, but generally it is from 2 to 10V. V-Trigger is used by Roland and Sequential Circuits synths, among others.
S-Trigger (“short circuit trigger”, sometimes called “negative trigger”). This one involves keeping voltage high normally, shorting the trigger circuit whenever the note should play. S-Trigger is used by Moog, Korg and Yamaha synths, among others.

Depending on the voltage level used, using the wrong combination of triggering mechanism would either yield no sound at all or would reverse all keypress events (i.e. sound will be produced with no keys pressed and muted on keypress).

On synthesizers, this signal is usually labelled as “Gate”, “Trig” or “S-Trig”.
Modern usage

Since the publishing of the MIDI standard in 1983, usage of CV/Gate to control synths has decreased dramatically. The most criticized aspect of the CV/gate interface is the allowance of only a single note to sound at a single moment of time.

However, the 1990s saw renewed interest in analog synthesizers and various other equipment, notably the Roland TB-303. In order to facilitate synchronization between these older instruments and newer MIDI-enabled equipment, some companies produced several models of CV/Gate-MIDI interfaces. Some models target controlling a single type of synthesizer and have fixed CV and Gate implementation, while some models are more customizable and include methods to switch used implementation.

CV/Gate is also very easy to implement and it remains an easier alternative for homemade / modern modular synthesizers. Also, various equipment, such as stage lighting sometimes uses CV/Gate interface. For example, a strobe light can be controlled using CV to set light intensity or color and Gate to turn an effect on and off. With the advent of non-modular analog synths, the exposure of synth parameters via CV/Gate provided a way to achieve some of the flexibility of modular synths. Some synths also could generate CV/Gate signals and be used to control other synths.

One of the main advantages of CV/Gate over MIDI is in the resolution. Most MIDI control messages use 7 bits or 128 possible steps for resolution. Control Voltage is analogue and by extension infinitely variable. There is less likelyhood of hearing the zipper effect or noticeable steps in resolution over large parameter sweeps. For this reason MIDI Pitch Bend uses 14 bits or 16,384 possible steps. There are ways to send higher MIDI resolution through the use of RPN’s and NRPN’s however in practice this is often difficult.

A major difference between CV/Gate and MIDI is that in many analogue synthesizers no distinction is made between voltages that represent control and voltages that represent audio. This means audio signals can be used to modify control voltages and vice versa. In MIDI they are separate worlds and there is no easy way to have audio signals modify control parameters.

Some software synthesizers emulate control voltages to allow their virtual modules to be controlled as early analog synths were. For example, Propellerheads Reason allows a myriad of connection possibilities with CV, and allows Gate signals to have a “level” rather than a simple on/off (for example, to trigger not just a note, but the velocity of that note)…

In 2009, MOTU released its Volta virtual instrument plug-in which allows audio workstation software with MIDI (and Audio Units compatibility) to precisely control any hardware device with a control voltage.

Electronic Music 1979

David Vorhaus Analogue Electronic Music 1979

This excerpt is taken from the BBC 1979 documentary entitled “The New Sound of Music” hosted by Michael Rodd – it speaks about inspiration and the possibilities that innovative gear offers an electronic musician.

Raymond Scott Pioneering Electronic Music Composer And Instrument Designer

Raymond Scott had a very long career as a bandleader, composer, and pioneer in electronic music. Like many very talented musicians, his name is largely unknown to the general public. He created one of the world’s first synthesizers, the Electronium.

The Electronium

Electronium Automatic Compsition & Performance Machine

Electronium Automatic Compsition & Performance Machine

An Electro-Mechanical Sequencer

An Electro-Mechanical Sequencer

Press Here To Enter The Raymond Scott Website

The Circle Machine

Raymond Scott Blog