An application of formal languages to the representation of musical processes is introduced. Initial interest was the structure of improvisation in North Indian tabla drum music, for which experiments have been conducted in the field as far back as 1983 with an expert system called the Bol Processor, BP1. The computer was used to generate and analyze drumming patterns represented as strings of onomatopeic syllables, bols, by manipulating formal grammars. Material was then submitted to musicians who assessed its accuracy and increasingly more elaborate and sophisticated rule bases emerged to represent the musical idiom.

Since several methodological pitfalls were encountered in transferring knowledge from musician to machine, a new device, named QAVAID, was designed with the capability of learning from a sample set of improvised variations supplied by a musician. A new version of Bol Processor, BP2, has been implemented in a MIDI studio environment to serve as a aid to rule-based composition in contemporary music. Extensions of the syntactic model, such as substitutions, metavariables, and remote contexts, are briefly introduced.