It is based on the same principle as sampling. However, the samples are split into small pieces of around 1 to 100 ms in duration. These small pieces are called grains. Multiple grains may be layered on top of each other, and may play at different speeds, phases, volume, and frequency, among other parameters.
At low speeds of playback, the result is a kind of soundscape, often described as a cloud, that is manipulatable in a manner unlike that for natural sound sampling or other synthesis techniques. At high speeds, the result is heard as a note or notes of a novel timbre. By varying the waveform, envelope, duration, spatial position, and density of the grains, many different sounds can be produced.
An example of granular synthesis. Note how the tiny snippets of sound (the grains) are initially distinct, but then blend together, generating a completely new timbre.
Both have been used for musical purposes: as sound effects, raw material for further processing by other synthesis or digital signal processing effects, or as complete musical works in their own right. Conventional effects that can be achieved include amplitude modulation and time stretching. More experimentally, stereo or multichannel scattering, random reordering, disintegration and morphing are possible.
The composer Iannis Xenakis (1960) was the first to explicate a compositional theory for grains of sound. He began by adopting the following lemma: "All sound, even continuous musical variation, is conceived as an assemblage of a large number of elementary sounds adequately disposed in time. In the attack, body, and decline of a complex sound, thousands of pure sounds appear in a more or less short interval of time ." Xenakis created granular sounds using analog tone generators and tape splicing. These appear in the composition Analogique A-B for string orchestra and tape (1959).[2]
Curtis Roads was the first to implement granular synthesis on a computer in 1974. [3]
Twelve years later, in 1986, the Canadian composer Barry Truax implemented real-time versions of this synthesis technique using the DMX-1000 Signal Processing Computer.[4] "Granular synthesis was implemented in different ways by Truax."[2]
Mutable Instruments Clouds – a digital, open source eurorack synthesizer module which has four factory set modes, the first and default being a granular processor[8]
Make Noise Morphagene – a eurorack synthesizer module built around microsound, or granular synthesis, in addition to Musique Concrète-inspired sound on sound audio manipulation[9][10]
Tasty Chips GR-1 - polyphonic granular synthesizer capable of 128 grains per voice, which can add up to a total of 1000+ grains simultaneously[11]
^Xenakis, Iannis (1971) Formalized Music: Thought and Mathematics in Composition. Bloomington and London: Indiana University Press.
^ abRoads, Curtis (1996). The Computer Music Tutorial. Cambridge: The MIT Press. p. 169. ISBN0-262-18158-4.
^Roads, Curtis (2001). Microsound. Cambridge, Massachusetts: MIT Press. ISBN0-262-18158-4.
^Truax, Barry (1988). "Real-Time Granular Synthesis with a Digital Signal Processor". Computer Music Journal. 12 (2): 14–26. doi:10.2307/3679938. JSTOR3679938.
Bencina, R. (2006) "Implementing Real-Time Granular Synthesis", in Greenbaum & Barzel (eds.), Audio Anecdotes III, ISBN1-56881-215-9, A.K. Peters, Natick. online pdf
." Xenakis created granular sounds using analog tone generators and tape splicing. These appear in the composition Analogique A-B for string orchestra and tape (1959).[2]