Chromatic Sound to Light Conversion System. It's really that simple. Unlike so many of the sound responsive systems out there, ColorChord looks at the chromatic properties of the sound. It looks for notes, not ranges. If it hears an "E" it doesn't care what octave it's in, it's an E. This provides a good deal more interesting patterns between instruments and music than would be available otherwise.
Background
----------
Developed over many years, ColorChord 2 is now getting close to alpha stages. ColorChord 2 uses the same principles as ColorChord 1. A brief writeup on that can be seen here: http://cnlohr.blogspot.com/2010/11/colorchord-sound-lighting.html
The major differences in ColorChord 2 is the major rewrite to move everything back to the CPU and a multitude of algorithmic optimizations to make it possible to run on something other than the brand newest of systems.
Currently, ColorChord 2 is designed to run on Linux. It's not particularly tied to an architecture, but does pretty much need a dedicated FPU to achieve any decent performance. Right now there aren't very many output options available for it. The most interesting one used for debugging is a vornoi-diagram-like thing called "DisplayShapeDriver."