Every other method on this course makes a wave. Granular synthesis takes a recording and cuts it into pieces too short to hear as sounds in their own right, then plays hundreds of them a second, overlapping, at any pitch, from any point. Alone, a grain is a click. Together, they are a cloud.
The idea: sound in quanta
In a paper published in Nature on 3 May 1947, "Acoustical Quanta and the Theory of Hearing", the physicist Dennis Gabor proposed that any sound can be described as a set of elementary grains, each a short pulse carrying both a time and a frequency. The composer Iannis Xenakis took the idea into music: his Analogique A-B of 1959, for string orchestra and tape, was built from grains made with tone generators and tape splicing, and his book Formalized Music of 1971 set out the theory. Curtis Roads was the first to run granular synthesis on a computer, in the 1970s. In 1986 Barry Truax made it work in real time on a DMX-1000 signal processor, and used it for his piece Riverrun.
What a grain is
Truax's definition is the one to keep: a grain is a small acoustic event, less than 50 milliseconds long and typically 10 to 30, and the technique produces them at densities of several hundred to several thousand per second. The grain's source can be a stored wave, an FM tone or a sample. Each grain has its own tiny envelope, so it fades in and out instead of clicking at the edges. Played slowly and sparsely, grains make a soundscape. Played fast and dense, they fuse into a note of a new timbre, and one you can hold forever, because the grains never run out.
The knobs
Mutable Instruments' Clouds, an open-documentation Eurorack module, puts the whole method on five knobs. Most granular plugins carry the same five under other names.
| What it sets | Knob |
|---|---|
| Where in the recording the grains are taken from | Position |
| How long each grain is | Size |
| The speed, and so the pitch, the grains play back at, independent of position | Pitch |
| How many grains per second, and so how much they overlap; past the centre, scattered at random | Density |
| The grain envelope, from square through triangle to a Hann window: rough to smooth | Texture |
Clouds keeps recording what it hears into a buffer of a few seconds and takes grains from that, playing between 40 and 60 of them at once; a freeze button stops the recording so you can play with the last few seconds for as long as you like. Ableton's Granulator III, Robert Henke's instrument for Live 12, works the same way with a sample or with live audio, and adds a loop mode for rhythmic material and a cloud mode for drones.
What it is for
Three things no other method does. Stretching: slow the position down while the pitch stays put and a one-second vocal becomes a minute of pad. Freezing: stop the position altogether and a chord, a cymbal or a breath becomes a sustained texture. Scattering: push the density into random and raise the size, and a voice turns to weather. It is also why a granular pad never sounds like a looped sample: the grains come from slightly different places every time.
Sources
Every date, name, figure and definition on this page comes from these pages, read on 2026-11-05.