Complex Networks of Harmonic Structure in Classical Music

Music is a ubiquitous, complex and defining phenomenon of human culture. We create and analyze complex networks representing harmonic transitions in eight selected compositions of Johann Sebastian Bach’s Well-Tempered Clavier. While all resulting networks exhibit the typical ‘small-world’-characteristics, they clearly differ in their degree distributions. Some of the degree distributions are well fit by a power-law, others by an exponential, and some by neither. This seems to preclude the necessity of a scale-free degree distribution for music to be appealing. To obtain a quality measure for the network representation, we design a simple algorithm that generates artificial polyphonic music, which also exhibits the different styles of composition underlying the various pieces