'The works I have made with KOAN symbolise the beginning of a new era'

One of my consistent interests has been the invention of "machines" and "systems" that could produce musical and visual experiences. Most often these "machines" were more conceptual than physical: the point of them was to make music with materials I specified, but in combinations and interactions that I hadn't.

Many of my own records, particularly the ambient pieces, were created using such systems. For example, a number of tape loops, each with different musical elements and of different length, were allowed to overlay each other arbitrarily. Because of the differing lengths it could have been several years before they fell back into sync, and so the music always appeared different.

Much as I loved those albums, I always wished that I could sell the generating system itself, rather than just a few minutes of its output. Early last year, I received from a company called Sseyo a CD of music that had been made by its software program called KOAN. A couple of the pieces were clearly in "my" style, but what surprised me was that I could have been proud of them. I got a copy of the KOAN "authoring tool" - the program by which one writes the rules for these pieces - and, after a few days of typical interface frustration, I took to it like a duck to water.

KOAN works by addressing the sound card in the computer. The computer sends instructions to that sound card and tells it what noises to produce and in what patterns. KOAN is a sophisticated way of doing this, enabling a composer to control about 150 parameters that specify things like sound- timbre and envelope, scale, harmony, rhythm, tempo, vibrato, pitch range etc, etc. Most of KOAN's instructions are probabilistic - so that rather than saying "do precisely this" (which is what a musical sequencer does) they say "choose what to do from within this range of possibilities". The KOAN program allows that range to be more or less specific - you could, if you so chose, write absolutely precise pieces of music with it, though this would probably be its least interesting use.

The works I've made with KOAN sound to me as good as anything I've done. They also symbolise to me the beginning of a new era in music. Until 100 years ago, every musical event was unique: music was ephemeral and unrepeatable and even classical scoring couldn't guarantee precise duplication. Then came the gramophone record, which captured particular performances and made it possible to hear them identically over and over again.

But KOAN and other recent experiments like it are the beginning of something new. From now on there are three alternatives: live music, recorded music and generative music. Generative music enjoys some of the benefits of both its ancestors. Like live music, it is always different. Like recorded music, it is free of time-and-place limitations - you can hear it when you want and where you want. And it confers one of the other great advantages of the recorded form: you can hear it as you work it out - it doesn't suffer from the long feedback loop characteristic of scored-and-performed music.

Edgar Wind, in his 1963 Reith Lectures, said: "...it might be argued that, in the last analysis, listening to a gramophone or a tape recorder, or to any of the more advanced machines of electro-acoustical engineering, is like listening to a superior kind of musical clock." I think it's possible that our grandchildren will look at us in wonder and say: "You mean you used to listen to exactly the same thing over and over again?"

I should stress that the idea of Generative Music is not original to me (though I think the name is). There have been many experiments towards it over the years, and a lot of my interest in the idea arose directly from Steve Reich's 1960's tape pieces such as "Come Out" and "It's Gonna Rain". But I think that this new linkage with an increasingly commonplace technology will make it a form in which many composers will wish to work.

n 'A Year with Swollen Appendices - the Diary of Brian Eno' is published on 6 May by Faber & Faber