What Is a Vocoder? How It Works, Vocoder vs Talkbox, and How to Use One

A vocoder is an effect that makes one sound talk with the voice of another. It analyzes the tone of a voice, band by band, and applies those changes to a synth or other instrument, so the synth plays your chords while pronouncing your words.

That's the robot choir sound on a lot of electronic, funk and pop records. It looks complicated from the outside, but there are only two inputs and a handful of controls to learn.

How does a vocoder work?

Every vocoder has two inputs. The modulator is the sound that does the talking, almost always a voice. The carrier is the sound that gets shaped, usually a synth. The vocoder never outputs the voice itself. You only hear the carrier, reshaped by the voice.

1. Split the voice into bands. A bank of band-pass filters divides the modulator into narrow frequency ranges, from the low body of the voice up to the hiss of consonants.
2. Follow each band's level. An envelope follower on every band measures how loud that slice of the voice is from moment to moment. Vowels light up different bands, which is how the vocoder tells an "ah" from an "ee".
3. Split the carrier the same way. A matching set of filters divides the synth into the same bands.
4. Apply the levels. Each voice band's level turns the matching carrier band up or down. Add the bands back together and the synth now has the tonal shape of speech.

More bands mean clearer words. A vocoder with only a few bands sounds vague and buzzy. One with 16 to 20 or more is usually intelligible, as long as the carrier is bright enough to give the upper bands something to work with.

The idea is older than synthesizers. Homer Dudley developed the vocoder at Bell Labs in the 1930s as a way to send speech using less bandwidth, by transmitting only the band levels instead of the full audio. Musicians picked it up decades later, and bands such as Kraftwerk made it part of the sound of electronic music.

What makes a good carrier?

The vocoder can only shape frequencies the carrier already contains. A sine wave has almost nothing above its fundamental, so it gives you a muffled hum. A saw wave, a supersaw or a stack of detuned oscillators is full of harmonics, which gives every band something to grab. Sustained sounds also work better than plucks, because a word only comes through while the carrier is playing.

Nova doesn't include a vocoder, but its Soft Strings preset shows the kind of sound that works well as a carrier: two saw oscillators an octave apart, five unison voices and a long sustain. Play a chord and listen to how much high end there is for a vocoder's upper bands to work with.

Vocoder vs talkbox

People mix these up because both make an instrument talk. They get there in completely different ways.

Peter Frampton's guitar solos and Roger Troutman's vocals with Zapp are the classic talkbox examples. Because a real mouth does the shaping, a talkbox gets consonants and vowel slides that vocoders struggle with. The trade-off is that it's a physical setup: a driver, a tube, a mic and a performer who can play and mouth the words at the same time.

If the sound you're after is a singer's own voice locked to notes, that's pitch correction, not vocoding. Our Tune plugin does that, from transparent fixes to the hard, stepped effect.

How to use a vocoder

The steps are the same in almost every DAW and vocoder plugin. Only the routing menus change.

1. Record or route a clear voice. Dry, close and evenly compressed works best. Room sound and reverb on the modulator blur the band levels.
2. Pick a bright, sustained carrier. Saws, supersaws and string pads with plenty of high end. Many vocoders include their own synth for this.
3. Connect the two. The voice goes to the modulator (often called the sidechain or analysis input) and the synth to the carrier. With a built-in synth, you only route the voice.
4. Play chords while the voice plays. The carrier's notes become the melody and harmony, so voice the chords the way you'd arrange a backing choir.
5. Adjust bands, attack and release. More bands for intelligibility, a short release for crisp words, a longer one for a smoother, more pad-like sound.
6. Bring back the consonants. Many vocoders have a sibilance, unvoiced or noise control that lets the hissy parts of S and T sounds through. Without it, words can sound mushy.

How to use the vocoder in Logic Pro

Logic's vocoder is EVOC 20 PolySynth, a vocoder with its own built-in synth as the carrier. Create a software instrument track and load EVOC 20 PolySynth on it. In the plug-in window header, open the Side Chain menu and choose the audio track with your vocal. Play or record MIDI chords on the instrument track while the vocal plays, and the synth will take on the words. If you don't want the dry vocal in the mix as well, send that track's output to an unused bus instead of muting it. More Logic notes are on our Logic Pro page.

Vocoders in other DAWs

Ableton Live includes a Vocoder audio effect that goes on the voice track and can take its carrier from another track. FL Studio includes Fruity Vocoder. Third-party vocoder plugins work the same way: one input for the voice, one for the synth, often through your DAW's sidechain routing. If you're new to plugin formats and routing, start with what a VST plugin is.

What are vocoders used for?

• Robot vocals. The obvious one: a lead or hook that sounds synthetic but still says words.
• Vocoded choirs. Play wide chords with a pad carrier under a single spoken line and you get an instant backing choir.
• Talking instruments. Use drums or a guitar as the modulator and a pad as the carrier, and the pad picks up the rhythm and tone of the part.
• Texture. Low in the mix, a vocoded double under the real vocal adds a synthetic sheen without anyone hearing it as an effect.

Famous songs with vocoder

• Kraftwerk, "The Robots" (1978): the robot voice most people picture when they hear the word vocoder.
• ELO, "Mr. Blue Sky" (1977): the vocoded "Please turn me over" line near the end.
• Herbie Hancock, "I Thought It Was You" (1978): a jazz-funk lead vocal sung entirely through a vocoder.
• Laurie Anderson, "O Superman" (1981): a hypnotic, vocoded voice over a looped "ha".
• Afrika Bambaataa & the Soulsonic Force, "Planet Rock" (1982): vocoder vocals that carried the Kraftwerk sound into hip hop and electro.