Abstract
Chord scale theory is an established method for teaching jazz improvisation that pairs chords with scales of corresponding sonority. Chord scale theory’s roots in tonal bebop and modal harmony limit its effectiveness with the tonally vague chord progressions that emerged in the 1960s post-bop movement and continue to be used in jazz today. This doctoral essay proposes a method of analysis and improvisation that adapts chord scale theory to the complex harmonies featured in post-bop music and modern jazz. Taking inspiration from transformational theory, I develop a system for analyzing tonally vague chord progressions by identifying common tones and semitone movement between successive chord scales. This demonstrates the ways pitch commonality and semitone movement create a sense of cohesion while avoiding tonal centers. These findings inform the development of new improvisation exercises designed to train musicians to hear and utilize the shared tones and semitone movements that give post-bop harmony its structure. This provides an updated approach to chord scale theory that adapts it to the linearly related harmonies pervasive in modern jazz.