Musicians sometimes imagine a melody as the “flow” of notes, moving forward unpredictably through time. When music involves a counterpoint, it is as though several streams join in a related, but continuously shifting, pattern. Composers such as John Cage experimented with aleatoric music (alea is Latin for dice), in which random events can create the musical equivalent of a delta. To do the same, start with a single “home” note, and toss a series of coins to determine whether the next note in a tune moves up or down in relation to its predecessor. A second tune can be generated in the same way, wandering out into a different configuration from the original starting point. Branching off from intermediate points in melodic lines can create subsidiary tunes. If several of the tunes are played at the same time, the contrapuntal nature of the piece will create surprising effects within the “delta” pattern. Use different instruments to hear the separate streams. You could also throw dice to decide how big the intervals should be. For more information about aleatoric music visit http:en.wikipedia.orgwikiAleatoric_music