Flash session: Jazz Hybridity in theory.

Voice-leading parsimony has long been recognized as a strong tonal currency in nineteenth century harmony, with further implications for popular music and jazz. Considerations of common-tone voice-leading in jazz, however, have tended to accord insufficient importance to triadic “extensions” such as 9ths, 11ths, 13ths (Larson 2009; Heyer 2012; McClimon 2016), despite the wealth of literature that deals with the 7th as a consonance in jazz (McFarland 2012; Strunk 2016). We believe that extensions should be given greater attention as they can prove crucial in achieving continuity and coherence in some of the more novel progressions that increasingly appear in recent works from prominent new artists such as Thundercat.

Providing a taxonomy of voice-leading patterns, we use simple adapted harmonic reduction techniques to offer a new methodology for considering extensions to the triadic core of jazz harmonies, which allows us to zoom into key progressions and visually track repeating patterns. We compare this type of common-tone coherence to other types of voice-leading syntax through integrated graphs. Working through songs from the Thundercat's album Drunk (2017), our key finding is that, while many of the chord progressions are difficult to explain according to conventional harmonic motion, the upper extensions act as binding agents that offer an alternative type of cohesion.