History of the Vocoder

1. Connor Fisher
HISTORY & EVOLUTION OF THE VOCODER

2. WHAT IS THE VOCODER?
In basic terms, the vocoder (short for voice encoder) can be described as a type of
synthesizer that produces sound based on speech input. More specifically, the vocoder is an
analysis and synthesis system. The concept arose in the late 1920’s- early 1930’s, originally
developed to be a speech encoder within telecommunication devices, with the intention to
code human speech for transmission.
Records show that the first models of the vocoder were developed in 1939 and 1940. Homer
Dudley a research physicist in New Jersey developed the Voice Operated Recorder (or
CODER). This was a system originally designed to test compression schemes for secure
transmission of voice signals over copper wire. The system was developed in 2 parts;
1939 saw the invention of the Vocoder Speech Synthesizer. This was a valve driven device
was played by a human operator. The device had two keyboards, buttons to recreate
consonants, a pedal for oscillator frequency control and a switch to turn off vowel sounds.
In 1940 the parallel band pass vocoder was invented. This device analysed and re-
synthesized speech.

3. THE VOCODER AND THE WAR
If you’ve listened to pop music over the past 40 years or so you’ve probably come across that
‘dalek-like’ sounding speech. That’s all thanks to the vocoder. However, as mentioned on the
previous slide, the vocoder didn’t start out that way. As a means to better transmit speech through
telecommunication devices, the vocoder also played a role during the second world war. When it
was discovered that Winston Churchill and Franklin D Roosevelt’s conversations were being
intercepted by the Germans, Bell Labs was commissioned to create a device to throw a spanner in
the Germans works, so to speak.
Presumably based somewhat on Dudley’s original designs for the CODER, Bell Labs under
commission during the second world war produced the vocoder in 1942 which enabled
conversations between Churchill and Roosevelt to be harder to intercept. The vocoder scrambled
the speech being transmitted making it almost impossible for the Germans to decipher, the
scrambled speech would be put back together at the receiving end where it could be understood.
The vocoder however was not without it’s flaws, whilst making the speech patterns harder to
intercept, pitch control was apparently and issue when transmitting speech patterns through the
vocoder, no-one minded sounding like a robot in order to protect top secret data but there’s a line
between robot and chipmunk. (Now you’re trying to imagine Winston Churchill as a chipmunk, if not,
why not?).

4. FROM MILITARY TO MUSIC
So while the vocoder was not originally designed for musical purposes it has indeed made it’s name
in the world of music. The vocoder went through an interesting transition from world war device to
musical effect in 1971, oddly enough on the soundtrack for “A Clockwork Orange”. On this
soundtrack, Wendy Carlos recorded a vocoder interpretation of Beethoven’s fourth movement of the
ninth symphony. Since this odd yet very interesting musical encounter the vocoder has taken to the
stage in many more musical numbers by various artists.
After A Clockwork Orange, the vocoder made it’s way into music studios. The vocoder was still a
pricey piece of kit to get your hands on but allowed for a lot more variation and interesting effects
when writing and producing music. The German band known as ‘Kraftwerk’ were believed to be the
first musicians to use the vocoder in their work, the bands music was primarily electronic so using
the vocoder made a lot of sense and as mentioned before, opens a lot of doors for new effects.
Later, in the 1980’s the vocoder made it’s debut on what is believed to be the first hip-pop vocoder
album recorded by Michael Jonzun, titles ‘Lost in Space’. Quite fitting for the robot-esque sound
properties of the vocoder and the sounds produced by the vocoder went well with the synthesizer,
the sounds produced on this album were then widely heard during that decade.
Whilst the vocoder it less prominent in to days musical societies and is perhaps a little taken for
granted nowadays, it still lives on, I’m sure there are many artists that still appreciate the Vocoder
and it’s successor, ‘autotune’ is something many artists and producers are all too familiar with.

5. SO HOW DOES IT WORK?
So as mentioned on the first slide the vocoder works in two parts.
The analyzer detected energy levels within sound samples measured across the audio
spectrum through a series of narrow band filters. The results of this analysis could then be
viewed graphically as frequency against time.
The synthesizer then reversed this process. The synthesizer scanned the data from the
analyzer and supplied the results to several filters, hooked up to a noise generator. This
combination of devices and functions then produced the sounds.
So as for it’s use during the second world war. The vocoder recognised the energy levels
within the speech samples and using filters was able to scramble the audio frequencies thus
creating the robot-like speech used to transfer transoceanic messages.

6. VOCODING – A TIMELINE
With it’s growing involvement in the musical world it was inevitable that the vocoder would
make it’s way into instruments somewhere down the line. It seems as if anyone who was
anyone wanted a piece of the vocoding action, so here’s a time line with a few insights into
how the vocoder developed following it’s use in the second world war.
1960. The Siemens Synthesizer, developed in Munich was the first synthesizer to include a
valve driven vocoding unit among it’s various oscillators and filter functions.
1967. A company by the name Sylvania created several devices that incorporated the
vocoders use of time related analysis of input signals as oppose to the previous, bandpass
filter analaysis.
1971. Wendy Carlos and Bob Moog modified several synthesizer models after studying
Dudley’s original unit in order to create their own vocoder to be used on the Clockwork
Orange Soundtrack.

7. VOCODING – A TIMELINE
1976. EMS produce a standalone and portable vocoder. The EMS studio vocoder (later
renamed the EMS 5000) was the worlds first commercially available vocoding unit and
amongst it’s users were Stevie Wonder, Kraftwerk and ‘Elektronische Musik’ pioneer
Stockhausen.
1977. EMS release the EMS 2000, a cut down version of the 5000. Sennheiser release the
VMS 201.
1978. The increase in mainstream vocoding. The popularity of artists such as Kraftwerk
among other artists caused many companies to begin production of vocoding units. KORG
release the VC-10.
1979. Roland release an ensemble/vocoder keyboard, named VP 330.
Late 1970’s – 80’s. This time period is considered to be the vocoders prime. Many artists,
including Pink Floyd, David Bowie, Kate Bush, Eurhythmics and more were all believed to
have used vocoders in their music.

8. VOCODING – A TIMELINE
1980 – present. EMS (UK), Synton (Holland), and PAiA (USA) have been, and still remain the
top manufacturers of vocoding units.
1996. Doepfer (germany) and ‘Music and More’ join the vocoding production wagon.
From the late 1990’s many standalone and software integrated vocoders have been produced
like the EVOC – 20 (Logic). Many other DAW’s such as Ableton also have built in vocoding
units that can be connected to MIDI controllers, keyboards etc.

9. VOCODING AND MIDI
When it comes to modern day music and music production you can’t really get a word in
edgeways without MIDI wanting to get involved and let you know what it’s all about. So of
course it was only natural the with the introduction of MIDI, vocoding would go yet another
step further. By using MIDI devices when using a vocoder, It allows the user to explore some
interesting new functions. MIDI keyboards can be used to change the pitch and key of the
speech input of a vocoder, also allowing you to play chords and melodies using your voice,
which opens up a lot of opportunities to be creative with a vocoder. Remember how the
Dalek’s talk in Doctor Who? All achieved through the use of a vocoder and a MIDI keyboard
to control the pitches.