 Granular Synthesis: an overview

Overview  Sounds are made up of a large number of particles!  Examples of granular sounds Leaves Traffic Babbling Brook

History  “ All sound is an integration of grains, of elementary sonic particles, of sonic quanta. ” – Xenakis 1971  First suggested as a computer music technique by Iannis Xenakis and Curtis Roads

Granular Synthesis particulars  Production of high density of small acoustic events called “ GRAINS ”  Allows time stretching or compression  Time and/or frequency-based processing  Numerous components in granular synthesis  Grain size, type, source, envelope  Grain density  Temporal arrangement of grains

Granular Synthesis basics

Grain sources  Granular synthesis can be generated from any sound source  True granular synthesis uses synthetic sound sources  Wave table (I.e. sine wave)  FM Synthesis  Can also granulate a sampled sound (sometimes called soundfile granulation)

“ The Grain ”  A “ grain ” is a slice of sound  Typically less than 50 ms in duration  Usually 10-30ms  Grains < 50ms = continuous texture  Grains > 50ms = discrete events

Grain Envelope  Each grain must have an envelope (ADSR)  Impacts how we perceive the resulting timbre  This is a “Hanning” envelope

Grain parameters

Grain Examples

Basics of Granular Synthesis

Grain Density  How many grain events take place per second  Can range from several hundred to several thousand!  Grains can overlap or be separated by silence

Types of Granular Synthesis  There are three methods of performing granular synthesis:  Pitch-synchronous  Asynchronous  Quasi-synchronous

Pitch-synchronous  Infrequently performed  Uses pitch detection and spectral analysis as a means to determine grains

Asynchronous  “Clouds of grains ” or “ Sonic Spray Gun ”  Random distribution of grains over some period of time  Algorithms determined grain placement  Results in organic and complex timbres

Aynchronous G.S.

Asynchronous G.S.

Quasi-Synchronous G.S.

Soundfile Granulation

Temporal manipulations  By manipulating the overlap between grains, we can expand or compress time

Temporal manipulations  We can create accelerandi or ritardandi (speed up or slow down)