Approximate Rhythms

hardware:   Sun 3/280, DEC Microvax II/Ultrix
software:   cmix

This was released as "music from the Winham Laboratory" on the Centaur Inner Voices CD (Centaur CRC 2076, part of the CDCM Computer Music Series). I started working on it while still a graduate student at Princeton back in 1986, but then interrupted work on it while I finished my dissertation. I completed the final section on our Sun at Columbia after I joined the faculty. The original two sections were done at a sampling rate of 28k, and the final SR used was 30k. We upsampled it for the CD. Computers just didn't go all that fast back then!

I sampled a bunch of percussion instruments that I had collected through the years that were combined with instruments from my grandfather's collection. The 'beat-coalescing' section that starts the piece (and recurs later) uses the idea behind the Karplus-Strong algorithm -- cycle through an array and average between successive numbers on each cycle -- and applies it in the 'macro' time domain to a randomly-generated set of hits. It's nifty because each group of hits will collapse to a different point. The calypso-like rhythm that results was an artifact of this process.

There are three main sections, the first uses 'skin' drums, the second draws upon 'wooden' instruments, and the third is from 'metal' instruments. There's that subtext for ya! The "helicopter break" in and the final helicopter sound are from recordings I was using for my dissertation. I had been sampling the ambient sounds around our house throughout the year (my "Four Seasons"...) and that helicopter flew right overhead during one of my recordings. Yikes!

This was a real breakthrough piece for me in that I really hit the use of compositional algorithms. This was made possible by the MINC parser interface to the cmix language, and I still use it all the time today. It is a very powerful tool for doing computer music.