Paulo Perfeito

Jazz Harmony and Plasticity: Chord-Scales, Nonfunctional Progressions and Modulatory Fields

This paper explores a new conceptual framework for Jazz harmony with implications for performative, compositional and analytical practices. Current tonal jazz practice deciphers every active harmonic structure as a defining mode that unifies and contextualizes a basic chord (commonly a 7th-chord type) within a given key: the chord-scale.
Grounded on recent harmonic studies of Jazz (Miller 1996 and Russell 2001), Perfeito advances a cognitive-based model for the exploration of chord-scale possibilities in a given improvisatory moment. The plethora of such possibilities is negotiated between the tonal function of a given active chord-scale and the larger tonal context dictated both by past harmonic events and the expected progression.

The negotiation between chord-scale and context thus entails a constant assessment of the dichotomy between change of key (modulation) and change of pitch center (tonicization). Such assessment is approached through an overall modulatory framework (Ribeiro-Pereira 2005), by considering the key-defining tritone as a permanent intervallic element, which is subject to harmonic reinterpretation.
Furthermore, the paper develops an analytical approach, which examines nonfunctional/modal progressions through modulatory lenses. Such approach generates an encompassing harmonic system, conceived as a modulatory field, which coordinates chord-scales based on common pitch-sets and their relation to harmonic tension.