This piece is a study of the technical and aesthetic aspects of "on-the-fly" audio programming for synthesis and performance. We use the new ChucK synthesis language, which supports real-time, sample-synchronous, concurrent audio programming, and a highly "on-the-fly" style of programming, in which the composer | performer |programmer augments and modifies multiple programs while they are running, without stopping or restarting.

"On-the-fly Counterpoint" begins with a blank ChucK program. As part of the performance, we project the entire process on the screen for the audience to see and follow. We construct the counterpoint piece-by-piece in real-time, using the facets of concurrent audio programming and on-the-fly programming in ChucK. Contrapuntal simultaneities can be separated and compartmentalized into autonomous, concurrent entities. We can program and reason about each entity independently, as well as interact with other entities and with the program as a whole.

This is part of our ongoing investigation into using code as an interactive and expressive musical instrument. It is also an instantiation of the ideas in our NIME2004 paper: "On-the-fly Programming: Using Code as an Expressive Musical Instrument".