Overview
- Any sound can be thought of as containing discrete particles/time segments (grains)
- Duration of an individual grain is short – usually 1 ms to 100 ms.
- Within an individual grain, sound parameters are fixed. Change occurs as you progress from grain to grain.
Parameters of Individual Grains
- Playback speed
- Index location (location in soundfile used to create grain)
- (maximum) amplitude
- Grain envelope
- Duration
- Panning
Parameters of Grain Combinations (Macro Controls)
- Frequency of grains (grains per second)
- Fixed or random rate of grain production
- Density of grains (the number of grains happening at one time)
- Number of grain streams (can be related to density)
Windows (Grain Envelopes)
- A window is a short-time amplitude envelope.
- The window shape can be chosen to emphasize legato connections between grains, discontinuity between grains, or anywhere in between.
Overlaps and Streams
- A stream is the individual series of grains occurring one after another.
- Multiple streams involve overlapping envelopes.
- Overlapping envelopes generally produce a smoother amplitude output.
High-Level (Macro) Organization
- The number of parameters to control, and the number of grains per second, require some type of macro control.
- Pitch-Synchronous organization analyzes the sound file ahead of time to set parameters so that a specified pitch will result. The parameter settings of individual grain parameters are linked. Kontakt tone machine uses pitch-synchronous organization.
- Asynchronous organization means that all grain parameters are specified independently of each other. Control functions are usually specified to change parameters over time.
- Quasi-synchronous organization indicates that some, but not all, parameters are linked. It is the most common organization offered in the programs we use (Cecilia and Kontakt time machine). Most often, grain duration determines the frequency of grains, as grains are created in succession. This organization leads to a type of AM synthesis.
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