FreeHorn is a computer music application, meant to accompany live instrumentalists. It has been performed many times over the past 10 years in a wide variety of circumstances and musical configurations.
The software allows users to set parameters (time, harmonic progression, rhythmic and density variables) that control the form of the piece. However, the piece has its own particular form: the continuous modulation of harmonic series' based on different fundamentals. This idea is taken from Polansky's Psaltery set of works (see his website for more examples).
Code for freeHorn was originally written by Phil Burk (with Larry Polansky) in Java, using Burk's Jsyn as the synthesis engine. Mike Winter contributed some modifications and features to the software some years later.
Some archival, live recordings are available at //http://eamusic.dartmouth.edu/~larry/archive.recordings.html
Various other notes (a partial manual) are at http://eamusic.dartmouth.edu/~larry/freeHorn/index.html