This is a classic case of one word having different meanings in different
contexts. For acousticians, recording engineers and designers of reverb systems,
it refers to the way sound is spread (and reduced in energy) when reflected from
irregular surfaces (by direect analogy with optical diffusion).

The term is also used by electro-acoustic composers and sound engineers, to
refer to the sometimes serendipitous  technique of playing back a (presumably
stereo) sound through a multi-speaker setup, by fiddling around with channel
sliders on a mixer (or using some hitec automated process. The term usually
embraces not just the live performance, but also the technical preparations in
setting up the speakers, mixer, and so on. 

So sound will be diffused by an acoustical space, but it will also be diffused
by the way it is presented over a speaker system in live performance.

I know of no literature about the latter meaning - it's probably best to go to a
few concerts and talk to the people twiddling the knobs!

Richard Dobson 

pete moss wrote:
> 
> there has been a word thrown around recently that i dont quite
> understand.  that word is diffusion.  i understand that it may be
> possible to play a stereo file into more than two channels, but how
> exactly does diffusion work?  do you just pan one channel between
> several others?  does anyone know of any good literature on the subject?
> 
> pete