Diachronic Changes in Jazz Harmony: A Cognitive Perspective

The present study examines both gradual and rapid changes occurring in 20th-century jazz harmonic practice. A newly-assembled corpus of 1,086 jazz compositions was used to test the idea that jazz music exhibits a mid-century decline in traditionally “tonal” chord usage. Evidence was found for slow, incremental changes in zeroth-order chord quality distributions, consistent with gradual, unconscious changes in harmonic usage. Typical tonal chord-to-chord transitions became less common between the 1920s and the 1960s, consistent with the hypothesis of tonal decline. Finally, use of root motion of an ascending perfect fourth dropped suddenly in the 1950s, suggesting that chord-to-chord transitions might be more susceptible to rapid change than chord frequency. Possible constraints on stylistic evolution are discussed.