The Sound Design and Synthesis course promises advanced sound sculpting: wavetable, FM, granular and additive synthesis. This chapter covers the last two - techniques that approach sound from opposite directions. Granular breaks existing sound into tiny particles; additive builds sound up from individual sine waves.
Granular synthesis
Granular synthesis cuts an audio sample into tiny fragments called grains - typically 10 to 100 milliseconds each - and plays them back, often many at once, in ways the original recording never could. The results range from smooth time-stretched textures to shimmering clouds, glitches and drones.
The controls
- Position - where in the sample grains are taken from. Moving it scans through the sample, independent of playback speed.
- Grain size - the length of each grain. Short grains sound buzzy and pitched; long grains preserve more of the original sound.
- Density - how many grains play per second. Low density sounds sparse and stuttery; high density becomes a smooth cloud.
- Pitch - the pitch of each grain, independent of the position and speed.
- Spray (randomisation) - random variation of position, pitch or timing. Adds movement and diffusion.
- Grain envelope - the shape of each grain's fade in and out. Smooth envelopes avoid clicks; sharp ones add texture.
- Pan spread - spreading grains across the stereo field.
What it is good for
- Extreme time-stretching - freezing a single moment of a sound and holding it indefinitely.
- Pads and atmospheres - from any source: a voice, a piano note, a field recording.
- Textures and glitches - stutters, clouds and scattered fragments.
- Turning noise into music - granular can make almost any recording playable and pitched.
Granular tools
Many DAWs and synths include granular engines - Logic's Alchemy, Ableton's Granulator, Arturia's Pigments - along with countless dedicated plug-ins and Reaktor ensembles. Native Instruments' long-running Absynth combined granular processing with several other synthesis methods in one instrument.
Additive synthesis
Every sound can be described as a set of sine waves at different frequencies and levels - its harmonics. Additive synthesis builds sounds by controlling those sine waves directly. Where subtractive synthesis starts with everything and removes, additive starts with nothing and adds.
The idea
- Each partial is a sine wave with its own frequency and level.
- Harmonic partials sit at whole-number multiples of the fundamental, producing pitched tones.
- Inharmonic partials sit elsewhere, producing bells, metals and noise-like sounds.
- Giving each partial its own envelope lets the timbre evolve in detail - the way real instruments' harmonics change after a note starts.
The Hammond organ's drawbars are a simple, mechanical form of additive synthesis: each drawbar adds a harmonic.
Controls in practice
Controlling hundreds of partials individually would be impossibly slow, so modern additive synths offer higher-level controls:
- Spectral filters that shape many partials at once.
- Odd/even balance - emphasising odd harmonics for hollow tones, even for richer ones.
- Stretch - spreading partials out of harmonic alignment for bell-like sounds.
- Resynthesis - analysing a recording and recreating it from partials, which can then be edited.
Additive tools
Logic's Alchemy offers additive synthesis and resynthesis; Image-Line's Harmor is a dedicated additive synth; and Native Instruments' Razor, built in Reaktor, is an additive synth known for aggressive, modern sounds.
Combining methods
Modern synths increasingly combine engines: a granular layer for texture, a wavetable for movement, FM for bite, a filter to shape it all. Understanding each method lets you choose the right tool - or combine them.
Do this now
- Load a vocal or field recording into a granular engine. Freeze the position and play it as a pad.
- Change grain size from very short to long and listen to the texture change; then raise density and spray.
- In an additive synth, build a tone by adding harmonics one at a time.
- Stretch the partials until the tone becomes bell-like.