What is granular synthesis?

In short:
Granular Synthesis is a method by which sounds are broken into tiny grains which are then redistributed and reorganised to form other sounds.

Slightly more verbose:

Granular synthesis is perceived as a relatively recent development in sound synthesis, but it can also be seen as a reflection of long-standing ideas about the nature of sound. Quantum physics has shown that sound can be atomically reduced to physical particles(Wiener 1964). This physical form of sound was first envisioned by the Dutch scientist Isaac Beeckman (Cohen 1984). He explained that sound travels through the air as globules of sonic data.

Later works including those by Gabor (Gabor 1946) and more recently Xenakis (Xenakis 1971), Roads (Roads 1988), and Truax (Truax 1990) has evolved the particle theory of sound into a synthesis method whereby the natural sound particle is imitated and magnified, referred to as a grain. The grain is then layered with other grain, either cloned or extracted through a similar process as the original to create different sounds and sonic textures. The original intent of the process described by Gabor was to reduce the amount of data required to convery an audio human communication, necessitated by the low band width, but rising usage of telecommunication devices in the 1940s (Gabor 1946).

Gabor's research came into the hands of Xenakis, who recognised a musical application for this work (Xenakis 1971). Xenakis' first works involving granular synthesis were created by splicing magnetic tape into tiny segments, rearranging the segments, and taping the new string of segments together. After attending a seminar conducted by Xenakis on this topic, Roads began experimenting with this idea on a computer. His first experiments were extremely time consuming, even when rendering just a one minute mono sound (we are not talking minutes here, nor hours, but days, usually weeks, depending on scheduling and transferring). After reading an article about granular synthesis written by Roads in 1978, Truax began developping a way to create granular synthesis in real-time, first realised in 1986. From this point on, granular synthesis has slowly become available to a growing number of musicians and sound artists.

What do I need to implement granular synthesis at home?

Depends on how you want to do it.

If you want to do it the original Xenakis way you will need a reel to reel tape recorder, a razor blade, sticky tape, and a lot of time.

If you want to use modern techniques you will need a computer. Any kind of computer will do, althought the faster your computer runs, the more you can accomplish at once. Any operating system will do. You will also need a computer program. Each operating system has its own programs.

Where can I get these programs??

There is a comprehensive download section on the Software page.

What is a grain?

A grain is a small piece of sonic data. In granular synthesis it will usually have a duration between 10 to 50 ms. The grain can be broken down into smaller components, the envelope and the contents. The envelope is used primarily so that there is no distortion and crunching noises at the beginning and end of the sample. The shape of the envelope though has a significant effect on the grain. The contents of the grain is audio. This can be derived from any source. Sine wave, square wave, audio sample, etc.

What is wavelet synthesis?

Wavelet synthesis is very closely related to granular synthesis except that it is more strict in its definition and construction. A granular synthesis grain can be set at any length arbitrarily, whereas a wavelet derives its "grain" length as determined by the pitch of the contents, using the wavelet transform. The wavelet is designed to start and end at 0 phase. Wavelet synthesis can be used for better pitch shifting and reproduction than granular synthesis, but it requires so much analysis that it is much slower to work with in a real-time environment.

What is grainlet synthesis?

It is actually another name for wavelet synthesis. It is the more commonly used term when referring to compositions created using the wavelet transform, whereas wavelet synthesis is the more commonly used term when referring to the analysis and reconstruction of audio. I personally prefer to use the term wavelet synthesis for all outcomes using the wavelet transform.

What is Glisson Synthesis?

A derivative of granular synthesis whereby the contents of each grain are modified with a glissando.

What is pulsar synthesis?

A form of particle synthesis whereby each grain is created as a pulsar, generated by an impulse generator.

This isn't enough information! Where can I find out more?

Right here on this web site! In the publications section you will find a number of papers written on granular synthesis. There are also a number of books worth reading such as Microsound, and The Computer Music Tutorial both by Curtis Roads.

----references used on this page-----
Cohen, H. 1984 Quantifying Music Dordrecht. D. Reidel Publishing Company.
Gabor, D. 1946 'Theory of Communication' The Journal of the Institution of Electrical Engineers. London: Unwin Brothers. 93(3): 429-457.
Roads, C. 1988 'Introduction to Granular Synthesis' Computer Music Journal. MIT Press 12(2):11-13.
Truax, B. 1990 'Composing with Real-time Granular Sound' Perspectives of New Music. USA: Hamilton Printing Company. 120-134.
Xenakis, I. 1971 Formalized Music. Bloomington: Indiana University Press.
Wiener, N. 1964 'Spatio-Temporal Continuity, Quantum Theory and Music' The Concepts of Space and Time. Dordrecht: D. Reidel Publishing Company. 539-546.