Composition and diffusion can be understood as two complementary andrelated processes: bringing sounds together, and spreading themout again in an organised fashion. In the Western tradition, these twoprocesses are frequently carried out by different people at different times,each drawing on specialised knowledge. The electroacoustic tradition, evenif much briefer, offers the possibility of the composer designing andimplementing both aspects of the music, and interrelating them in highlyspecific ways. Computer control offers the greatest precision in dealingwith the complexities of these processes, even though, at present, separateprograms are usually required.