Harmony in the Polyphonic Songs of Epirus: Representation, Statistical Analysis and Generation

This paper examines a previously unstudied musical corpus derived from the polyphonic singing tradition of Epirus employing statistical methods. This analysis will mainly focus on unique harmonic aspects of these songs, which feature, for instance, unresolved dissonances (major second and minor seventh intervals) at structurally stable positions of the pieces (e.g. cadences). Traditional triadic tonal chord types are inadequate for this corpus’ unconventional harmonic language; pc-set theoretic tools are too general/abstract. A novel chord representation has been devised that adapts to different non-standard tonal harmonic spaces. In the General Chord Type (GCT) representation, the notes of a harmonic simultaneity are re-arranged, depending on a given classification of intervals (that reflects culturallydependent notions of consonance/dissonance), such that abstract idiom-specific types of chords may be derived. Based on these harmonic representations, statistical analyses are performed that provide insights regarding underlying harmony and, especially, on the idiosyncratic use of consonance/dissonance within this idiom. Then, characteristics of harmonic successions are examined via statistical analysis of the common chord transitions in the idiom. Finally, the learned statistical features are used to generate new harmonisations in the Epirus-song style for unseen Epirus-song melodies or for melodies from other distant idioms.