Song 2
Audio
Song 2:
Score
Evolutionary Process
Song 2 started from an original monophonic melody composed by undergraduate Marie E. Norton.
The second layer was added by inputting this melody into the rhythm and pitch networks of the subsequent accompaniment populations.
This second layer then served as input to the pitch and rhythmic CPPNs for layers 3 and 4. The pitch CPPN for layer 5 took the output
from layer 2 as input, but the rhythm network only had a bias (i.e. constant) input. Finally, the inputs for the pitch network for layer
6 were layers 3, 4, and 5, while the inputs to the rhythm CPPN were layer 4 and a measure timing signal first introduced for NEAT Drummer
by Hoover and Stanley (2009) that gives the network a sense of where
the song is within the measure. All of the layers finally combined to create a single, multipart piece in which each line is functionally related
to the others. Each layer took as few as three to as many as five generations to evolve.
The key decisions made by the users are in general from which tracks to generate more tracks. Of course the users also performed the IEC selection operations to breed each new layer. Importantly, none such decisions require musical expertise.
