Evolutionary music

Evolutionary music is the audio counterpart to Evolutionary art, whereby algorithmic music is created using an evolutionary algorithm. The process begins with a population of individuals which by some means or other produce audio (e.g. a piece, melody, or loop), which is either initialized randomly or based on human-generated music. Then through the repeated application of computational steps analogous to biological selection, recombination and mutation the aim is for the produced audio to become more musical. Evolutionary sound synthesis is a related technique for generating sounds or synthesizer instruments. Evolutionary music is typically generated using an interactive evolutionary algorithm where the fitness function is the user or audience, as it is difficult to capture the aesthetic qualities of music computationally. However, research into automated measures of musical quality is also active. Evolutionary computation techniques have also been applied to harmonization and accompaniment tasks. The most commonly used evolutionary computation techniques are genetic algorithms and genetic programming.

History
NEUROGEN (Gibson & Byrne, 1991) employed a genetic algorithm to produce and combine musical fragments and a neural network (trained on examples of "real" music) to evaluate their fitness. A genetic algorithm is also a key part of the improvisation and accompaniment system GenJam which has been developed since 1993 by Al Biles. Al and GenJam are together known as the Al Biles Virtual Quintet and have performed many times to human audiences. In 1997 Brad Johanson and Riccardo Poli developed the GP-Music System which, as the name implies, used genetic programming to breed melodies according to both human and automated ratings. Several systems for drum loop evolution have been produced (including one commercial program called MuSing).

Recent work
The EvoMUSART workshops (2007 2006 2005 2004 2003) on evolutionary music and art are one of the main outlets for work on evolutionary music.

The EuroGP Song Contest (a pun on Eurovision Song Contest) was held at EuroGP 2004. In this experiment several tens of users were first tested for their ability to recognise musical differences, and then a short piano-based melody was evolved.

Al Biles gave a tutorial on evolutionary music at GECCO 2005 and co-edited a book on the subject with contributions from many researchers in the field.

The Evolutionary Remix Machine is a web-based loop generator which uses genetic programming for sound synthesis, sample processing (effects), rhythm and melodic composition. Loop fitness is provided by the listener over the internet.

The GeneticDrummer is a Genetic Algorithm based system for generating human-competitive rhythm accompaniment.

Links
Al Biles' Evolutionary Music Bibliography - also includes pointers to work on evolutionary sound synthesis.

Books
Creative Evolutionary Systems by David W. Corne, Peter J. Bentley