Week 8 Readings: Algorithmic Composition

This week you're asked to do some reading and listening on topics related to "algorithmic composition" (composition by computer program), and to try your hand at programming with randomness and probability.

One of the earliest examples of algorithmic composition was the "Musikalisches Würfelspiel" (musical dice game), the most famous example of which is attributed to W.A. Mozart. You can see a copy of the musical score, with instructions Links to an external site. of how the procedure works, and you can hear examples Links to an external site. someone has programmed online. (The piece consists of two parts, termed minuet and trio, and most commonly each of the two parts is repeated, followed by a return to the first part: M M T T M. The linked program will compose both parts for you, but does not intelligently play the form correctly.)

Here are a few examples of mathematical/musical algorithms in Max. Try some of them out, and try to understand how they work.
• Algorithmic composition with mathematical expressions.
• Cellular automaton to control oscillators. (This patch doesn't control overall amplitude very well, and tends to clip, so you may want to turn down the volume of the patcher window.)
• Chaos algorithm for choosing pitches.
• Probability of playing or not playing repeated notes.
• Minimalist composer of changing loops.
• Automated blues "improviser"

Read the articles titled "A simple probabilistic decision Links to an external site." and "Probability distribution Links to an external site.". Try the patches and try to understand how they work. (You'll need to download the "gamble" abstraction and save it with the name "gamble" in order for the second patch on that page to work.)

Insofar as you have the time, try doing some simple experimentation with probability distributions of notes, timings, etc. to get a feel for the role that probability can play in music.

Here are three (optional) essays by Christopher Dobrian, musing on the topics of Intuition Links to an external site. and Randomness Links to an external site. and Randomness and Noise Links to an external site. as they apply to algorithmic composition.