As I was going through the audio CD accompanying Perry Cook's book, "Music Cognition and Computerized Sound", I came across this sound. The very complicated harmonic beat patterns it exhibits, intrigued me and so I decided to implement it in Matlab. It is easy to understand the algorithm by looking at the source code: risset_beats.m.
(Note that you can click on each spectrogram for a larger view and on each sub-title to listen to the actual sound.)
You can also take a look at Lonce
Wyse's implementation in Java