Definition
Granular synthesis breaks a sound into very short grains (from about 1 to 100 ms, often 10–50 ms), each with its own envelope (window), and recombines them into dense or sparse clouds. The theoretical ideas go back to the physicist Dennis Gabor (1940s, acoustic “quanta”) and to the music of Iannis Xenakis (Analogique B, 1959); Curtis Roads made the first computer implementations in the 1970s and wrote its theory in “Microsound” (2001); Barry Truax developed the real-time version in the 1980s (Riverrun, 1986).
Main parameters
- Source: a sample (granulating a file) or an oscillator.
- Position: the point in the file from which grains are read; moving it slowly gives a time-stretch, stopping it “freezes” the sound.
- Grain size: below ~20 ms the window's timbre prevails (buzz, noise); 30–100 ms preserves the source's identity.
- Density (grains per second): few grains = pointillistic texture; many = continuous flow.
- Spray / jitter: randomness of the position; increases the “cloud” effect and reduces periodic artifacts.
- Pitch of the grains and its randomness; direction (forward, backward, random).
- Window (Hann, Gaussian, trapezoid): soft shapes = smooth sound; steep windows = clicks and graininess.
- Random pan per grain: huge stereo width.
Uses in production
- Pads and drones from any recording (a piano note, a voice, a field recording): slow position, grains 50–80 ms, high density, medium spray, reverb.
- Extreme time-stretch without changing pitch (for example stretching a 1-second sample to 30).
- Glitch and stutter: short grains, low density, random pitch.
- Risers and FX: density and pitch rising together.
- “Frozen” vocal for bridges and intros: freeze a syllable and move the position slightly.
Instruments
Fruity Granulizer (stock in FL Studio), Ableton Granulator III / II, Output Portal, Arturia Pigments (granular engine), Native Instruments Kontakt (granular time-stretch modes), Max/MSP and Pure Data for those who want to build their own. Many DAW time-stretches (in FL Studio, the clips' stretch modes) use granular techniques.
Example in A minor
Take an Am(add9) chord played on piano (A2 – E3 – B3 – C4), load the file into Granulizer or Pigments: grains 60 ms, high density, spray 20%, position slowly scrolling from 30% to 70% over 8 bars, random pitch ±5 cents, random pan 50%. High-pass filter at 150 Hz and long hall reverb: it becomes the intro pad of a lo-fi or ambient track. For the bridge, freeze the position and transpose the grains up +12 semitones for a shimmer.
Typical problems
- Periodic artifacts (buzz at the density frequency): increase the spray or use unsynchronized density.
- Transient loss: granulation smears the attacks; for drums use other stretch methods.
- Phase and mono: random pan can give a very wide but unstable image in mono; check the correlation.
- CPU: very high densities are heavy; render to audio (see “Resampling”).
Exercise
- Record 2 seconds of any object (a cup, keys), granulate it and derive three sounds: pad, rhythmic texture, riser.
- Compare a granular × 4 time-stretch with a phase-based one (phase vocoder, if your DAW offers it): which preserves the timbre better?
- Build an 8-bar intro using only material granulated from your own track (vocal or piano).
Connections
“Sampling and samplers”, “Resampling”, “FX and risers”, “Pad design”, “Sound design for film and video games”.