In recent years, I have been interested in learning about polyrhythms, "the simultaneous sounding of two or more independent rhythms" (
http://en.wikipedia.org/wiki/Polyrhythm) and have been utilizing them in some of my compositions.
Recently, I've been reading about Euclidean Rhythms, which is a method of using the Euclidean algorithm (
http://en.wikipedia.org/wiki/Euclidean_algorithm) to compute rhythmic patterns. Briefly, this method allows one to equally distribute a number of pulses (k) in a given interval (n). For example, 5 k 9 n, or
E(5,9), would look like [x . x . x . x . x]. Turns out, this rhythm is also known as the popular Arab rhythm
Agsag-Samai (among other names).
To hear the results, create a clip in your DAW that is 9 steps (usually 1/16 notes) long, arrange your beats as marked above and loop it. Start combining multiple clips of Euclidean rhythms on different tracks (not necessarily just drums) and you start to hear interesting polyrhythms. Note, each pulse doesn't have to be the same note or sound. Here's a list of resources for those interested in more:
The Euclidean Algorithm Generates Traditional Musical Rhythms -
http://cgm.cs.mcgill.ca/~godfried/publications/banff.pdf (PDF)
The original paper by Godfried Toussaint, which isn't as math-intensive as one might think. It also contains a good breakdown of many of the
E(k,n) combinations.
Euclidean Rhythm MIDI File Resource in Ableton Live -
http://www.ageofthewheel.com/2011/03/euclidean-rhythm-midi-file-resource-in.htmlA good overview, including an Ableton set containing clips of every
E(k,n) combination.
Generating african rhythms using the euclidean algorithm by Wesen -
http://ruinwesen.com/blog?id=216One of the earliest implementations, including code and hardware implementation.
Euclidean sequencer Max for Live version by Robin Price -
http://registeringdomainnamesismorefunthandoingrealwork.com/blogs/?p=426A M4L midi device for generating rhythms. I have used this but find making my own clips to be easier when arranging.
Eckel VST -
http://www.shuriken.se/?page_id=97A midi generating VST based on the Euclidean algorithm.
These two articles from the Create Digital Music blog give more background, compile more resources and tools:
Drop me a line to share techniques, clips, finished tracks or if you're interested in more.