Granular synthesis is a sound synthesis method for digital musical instruments (synthesizers) that operates on the microsound time scale. It is often based on the same principles as digital sampling but often includes analog technology. The samples are not used directly however, they are split in small pieces of around 1 to 50 ms (milliseconds) in length, or the synthesized sounds are very short. These small pieces are called grains. Multiple grains may be layered on top of each other all playing at different speed, phase and volume.

The result is no single tone, but a sound scape, often a cloud, that is subject to manipulation in a way unlike any natural sound and also unlike the sounds produced by most other synthesis techniques. By varing the waveform, envelope, duration, spatial position, and density of the grains many different sounds can be produced.

It is essential that the grain sizes are varied rather than being uniform; uniform grains can result in an audible frequency generated at the same frequency as the grains themselves.

The result is usable as sound effects or as raw material for further processing by other synthesis or DSP effects.

Canadian composer Barry Truax was one of first to implement real-time versions of this synthesis technique.

See also

• Frequency modulation synthesis
• Subtractive synthesis
• Additive synthesis
• Digital waveguide synthesis
• Physical modelling synthesis

Further reading

• Roads, Curtis (2001). Microsound. Cambridge: MIT Press. ISBN 0262182157.