VI. Jazz
Chord-Scale Theory
John Kocur
Key Takeaways
Chord-Scale Theory is an approach to improvising that relates chords to scales.
- The name “Chord-Scale Theory” comes from the idea that the notes of a thirteenth chord can be rearranged as a seven-note scale.
- To determine chord-scales, identify key centers and chord functions through Roman numeral analysis.
- Roman numerals can be related to mode numbers. For example, if a chord is a ii chord in a major key, the second mode (dorian) can be used to color that chord.
- When playing chord-scales, place chord tones on the downbeat to connect improvised melodies to the chord progression.
This book covers modes from many different angles. For more information on modes, check Introduction to Diatonic Modes (general), Modal Schemas (pop), Diatonic Modes (20th/21st-c.), and Analyzing with Modes, Scales, and Collections (20th-/21st-c.).
One of the challenges of improvising jazz is making choices about pitches while also paying attention to groove, interaction, and narrative form. The Chord-Scale Theory is a method, taught at the Berklee College of Music and many other colleges and universities, that facilitates pitch choices in jazz improvisation. Chord-Scale Theory is based on George Russell’s Lydian Chromatic Concept of Tonal Organization ([1953] 2001), and it was popularized by jazz educators Jamey Aebersold, David Baker, and Jerry Coker.
The basic concept is that every chord comes from a parent scale; or, to put it another way, every chord in a progression can be colored by a related scale. For example, a Dmi7 chord extended to the thirteenth consists of the notes D, F, A, C, E, G, and B, which are identical to the notes of the D dorian mode stacked in thirds (
). Therefore, when confronting a Dmi7 chord in a chord progression, an improvising musician could choose to improvise using the notes of the D dorian mode to create new melodies.
Basic Chord-Scale Relationships
Starting a major scale on each of its seven notes will yield seven different modes. Each of the modes will have a different pattern of half steps and whole steps and thus a different color. (For more information, see Introduction to Diatonic Modes and/or Diatonic Modes).
Since the ii–V–I schema is so common in jazz standards, the three chord-scale relationships in are often taught first. shows these three relationships within the context of a ii–V–I progression in C.
| Chord quality | Mode | Example |
|---|---|---|
| minor seventh chord | dorian | Dmi7 = D dorian |
| dominant seventh chord | mixolydian | G7 = G mixolydian |
| major seventh chord | ionian | Cma7 = C ionian |
A beginning improviser might approach a song consisting mainly of ii–V–I progressions by simply applying the dorian mode to minor seventh chords, the mixolydian mode to dominant seventh chords, and the ionian mode to major seventh chords. As
shows, an improvised melody can imply a harmony by placing chord tones on the downbeats, and a seven-note mode can be though