It is based on the same principle as sampling. However, the samples are not played back conventionally, but are instead split into small pieces of around 1 to 50 ms. 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.
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).
Canadian composer Barry Truax was one of the first to implement real-time versions of this synthesis technique. "Granular synthesis has been implemented in different ways, notably by the Canadian composer Barry Truax."
- Csound – comprehensive music software including granular synthesis (overview over granular synthesis opcodes)
- SuperCollider – programming language for real time audio synthesis
- Reaktor – visual programming environment for sampling, granular sampling, sequencing and modular synthesis
- Max/MSP – graphical authoring software for real-time audio and video
- Pure Data (Pd) – graphical programming language for real-time audio and video
- ChucK – audio programming language for real-time audio synthesis
- Real-time Cmix – programming language for real-time audio synthesis, including several algorithms for granular synthesis
- AudioMulch – modular audio software for real-time audio manipulation
- SoundGrain - graphical interface where users can draw and edit trajectories to control granular sound synthesis
There are now many dedicated devices available for exploring granular synthesis without using a computer. Many of them are in the Eurorack modular synthesizer format, such as:
- ADM02 Grainshift by Audio Damage
- Clouds by Mutable Instruments
- g0 by Mungo Enterprises
- Grains by Ginko Synthese
- GXN by Mordax Systems
- grandPa by Bastl Instruments
- Nebulae by Qu-Bit Electronix
- Particle Granular Delay by Red Panda Lab
- Morphagene by Make Noise
Standalone devices include:
- GR-1 by Tasty Chips Electronics
- Digital signal processing
- Micromontage audio montage on the time scale of microsounds
- Texture synthesis, analogous process for images
- Xenakis, Iannis (1971) Formalized Music: Thought and Mathematics in Composition. Bloomington and London: Indiana University Press.
- Roads, Curtis (1996). The Computer Music Tutorial. Cambridge: The MIT Press. p. 169. ISBN 0-262-18158-4.
- Truax, Barry (1988). "Real-Time Granular Synthesis with a Digital Signal Processor". Computer Music Journal. 12 (2): 14–26. doi:10.2307/3679938. JSTOR 3679938.
- "Granular Synthesis" by Eric Kuehnl
- "The development of GiST, a Granular. Synthesis Toolkit Based on an Extension of the FOF Generator" by Gerhard Eckel and Manuel Rocha Iturbide
- Searching for a global synthesis technique through a quantum conception of sound by Manuel Rocha Iturbide
- Further articles on Granular Synthesis
- Bencina, R. (2006) “Implementing Real-Time Granular Synthesis,” in Greenbaum & Barzel (eds.), Audio Anecdotes III, ISBN 1-56881-215-9, A.K. Peters, Natick. online pdf
- Miranda, E. R. (2002). Computer Sound Design: Synthesis Techniques and Programming. Oxford: Focal Press. ISBN 0-240-51693-1.
- Roads, Curtis (2001). Microsound. Cambridge: MIT Press. ISBN 0-262-18215-7.
- Wilson, Scott (2011). The SuperCollider Book. Cambridge: The MIT Press. ISBN 978-0-262-23269-2.
- Iturbide, Manuel Rocha (1999). "Doctoral Thesis: Les techniques granulaires dans la synthèse sonore". ArteSonoro.net. University of Paris VIII.
- Curtis Roads (2004). CD accomanying Microsounds. MIT Press. ISBN 0-262-18215-7. Contains excerpts of nscor and Field (1981). Microsounds at Discogs.
- Iannis Xenakis. Analogique A-B (1959), on Alpha & Omega at Discogs and Music For Strings at Discogs