A Novelty Search and Power-Law-Based Genetic Algorithm for Exploring Harmonic Spaces in J.S. Bach Chorales

We present a novel, real-time system, called Harmonic Navigator, for exploring the harmonic space in J.S. Bach Chorales. This corpus-based environment explores trajectories through harmonic space. It supports visual exploration and navigation of harmonic transition probabilities through interactive gesture control. These probabilities are computed from musical corpora (in MIDI format). Herein we utilize the 371 J.S. Bach Chorales of the Riemenschneider edition. Our system utilizes a hybrid novelty search approach combined with power-law metrics for evaluating fitness of individuals, as a search termination criterion. We explore how novelty search can aid in the discovery of new harmonic progressions through this space as represented by a Markov model capturing probabilities of transitions between harmonies. Our results demonstrate that the 371 Bach Chorale harmonic space is rich with novel aesthetic possibilities, possibilities that the grand master himself never realized.