Structural segmentation of music based on repeated harmonies

In this paper we present a simple, yet powerful method for deriving the structural segmentation of a musical piece based on repetitions in chord sequences, called FORM. Repetition in harmony is a fundamental factor in constituting musical form. However, repeated pattern discovery in music still remains an open problem, and it has not been addressed before in chord sequences. FORM relies on a suffix tree based algorithm to find repeated patterns in symbolic chord sequences that are either provided by machine transcriptions or musical experts. This novel approach complements other segmentation methods, which generally use a self-distance matrix based on other musical features describing timbre, instrumentation, rhythm, or melody. We evaluate the segmentation quality of FORM on 649 popular songs, and show that FORM outperforms two baseline approaches. With FORM we explore new ways of exploiting musical repetition for structural segmentation, yielding a flexible and practical algorithm, and a better understanding of musical repetition.