How Vocoders Work - Arturia VOCODER V User Manual

1.2. How Vocoders Work

Traditional vocoders have two inputs and one output. Both inputs need to receive audio, or
there is no effect. The two inputs are:
Modulator The usual input is speech from a microphone, although drums have also become
a popular modulation source. However, Vocoder V also includes a sampler player for playing
back up 12 different samples. These can include sound sources like drum loops, sound
effects, percussion, rhythm guitar, and more; you are not limited to vocal sounds.
Carrier The modulator modifies the carrier's sound. Usually this is a sustained sound, like
a synthesizer pad, choir, string section, and the like. Vocoder V features a full-featured
synthesizer for the carrier. The vocoder impresses the modulator's speech characteristics
onto the carrier, which is how the modulator makes the carrier "talk."
With analog vocoders, the main elements are filter banks, VCAs, and envelope followers.
Vocoder V recreates these elements digitally, but the principle of operation is the same
A vocoder contains two identical filter banks that cover specific bands throughout the audio
spectrum, somewhat like a graphic equalizer. Vocoder V's filter bank uses 16 filters to create
16 frequency bands.
The carrier goes through one filter bank, where each filter output feeds a DCA (digitally
controlled amplifier, the digital equivalent of an analog synthesizer's VCA). Each DCA
therefore controls a carrier band's level.
The modulator goes through an identical filter bank, but each filter feeds an envelope
follower that controls the corresponding carrier filter's level. For example, speech produces
energy at different frequencies, so the modulator envelope followers control the carrier filter
VCAs that correspond to speech frequencies. Or, if a kick drum is the modulator, then only
the carrier's low-frequency filters will be triggered to let audio through.
Another vocoding element is adding noise selectively, which improves intelligibility with
vocal effects. The noise can reproduce fricatives (consonants that result from friction in the
mouth, like "s" or "f"). Vocoder V includes a way to adjust the amount of noise injected in
response to fricatives, which makes vocal effects much clearer.
Remember that vocoders are not only useful with voice—you can obtain exciting, rhythmic
effects by using a modulation source like drums with any sustained carrier source, such
as guitar power chords. The chords become more interestingly rhythmically, and sync with
the drums. Ultimately, Vocoder V can do everything traditional vocoders do—but also offers
many new capabilities.
4 Arturia - User Manual Vocoder V - Welcome to Vocoder V