Genetic Hierarchical Music Structures
Charles Warren Fox · 2006
Music has structure at many levels, from grand arrange-ments of verses and choruses down to patterns in small riffs and themes. A bracketed L-system — the SARAH language — is used to represent compositions in terms of these hierarchical structures, allowing genetic pro-gramming to meaningfully mutate and crossbred com-positions at all levels of structure. Automated com-position becomes possible, using evolution with hu-man aesthetic judgment as a fitness function. SARAH is also human-readable and can be used as a human tool for rapid structural composition development; or as a semi-automated composition system, mixing hu-man and evolved contributions. The system has bred pleasing compositions starting from basic musical ma-terials and has also been used to crossbreed Bach with the Spice Girls: these examples are presented as audio files.