Granular Synthesis:

an overview

Overview

Sounds are made up of a large number of particles!

Examples of granular sounds

LeavesTraffic

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.

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)