With historical roots in the work of composer Iannis Xenakis, this term is currently strongly associated with the work of Curtis Roads. Broadly, the term refers to conceiving of and representing sound in terms of particles. These sounds fall within the domain that Roads calls the "micro time scale". He defines this scale as one that embraces transient audio phenomena, a broad class of sounds that extends from the threshold of timbre perception (several hundred microseconds) up to the duration of short sound objects (ca. 100 milliseconds). Roads has recently published a book entitled Microsound (Cambridge, MA: MIT Press, 2001).
See also:Grain, Granular Music, Granular Synthesis and Resynthesis
Bibliography: Truax, Barry (1995b). La composition basée sur le timbre avec son granulaire