WolframTones works by taking simple programs from Wolfram's computational universe, and using music theory and Mathematica algorithms to render them as music. Each program in effect defines a virtual world, with its own special story. WolframTones supports multiple instruments, as well as percussion. Everything is always derived from a single underlying cellular automaton pattern. But different instruments can be set up to pick off different aspects of the pattern--say to correspond to a melodic line or a bass track. WolframTones also supports a number of algorithms for deriving percussion from cellular automaton patterns. via tones.wolfram.com