Bits & Bytes
LOUIS, DUKE, MILES--AND MAC?
CAN A COMPUTER IMPROVISE jazz solos in the manner of Louis Armstrong or Thelonius Monk? A program written by John A. Biles, a trumpet-blowing computer scientist at Rochester Institute of Technology in Rochester, N.Y., for his Macintosh falls short of that lofty goal. But using what is called a genetic algorithm, Biles's GenJam manages to entertain off-campus audiences in live sessions with its creator.
Biles developed GenJam as a means of exploring the promising field of genetic algorithms. These programs evolve by mutating under the influence of outside stimuli--a digital form of Darwinian natural selection. Biles begins by describing a tune's chord progression to GenJam. Then, connected to a Yamaha tone generator, the system emits sequences of randomly selected licks, or preprogrammed tenor sax phrases, that it alters to harmonically match each chord, according to standard jazz theory.
As he listens, Biles pushes one key or another to reward or punish GenJam for its improvisations. That way, Biles says, with each run-through of a tune, GenJam tends to replace bad phrases with better ones. So far, he has no plans to make it a commercial product.EDITED BY WILLIAM J. WINKLER