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 13th chord can be rearranged as a seven-note scale.
• To determine chord-scales, identify key centers and 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 2nd mode () 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, and 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 Dm7 chord extended to the 13th 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 (Example 1). Therefore, when confronting a Dm7 chord in a chord progression, an improvising musician could choose to improvise using the notes of the D dorian mode to create new melodies.

Example 1. A Dm13 chord and a D dorian scale have identical pitches.

# Basic Chord-Scale Relationships

Starting a major scale on each 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 Intro to Modes and/or Diatonic Modes).

Since the ii–V–I schema is so common in jazz standards, the three chord-scale relationships in Example 2 are often taught first. Example 3 shows these three relationships within the context of a ii–V–I progression in C.

Chord quality Mode Example
minor 7th chord Dorian Dm7 = D dorian
dominant 7th chord Mixolydian G7 = G mixolydian
major 7th chord Ionian Cmaj7 = C ionian

Example 2. Basic chord-scale relationships.

Example 3. Chord-scale relationships in a ii–V–I progression in C.

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 Example 4 shows, an improvised melody can imply a harmony by placing chord tones on the downbeats, and a seven-note mode can be thought of as a four-note seventh chord with three passing tones $(\hat{2}$, $\hat{4}$, $\hat{6})$ or extensions (9th, 11th, 13th).

Example 4. The basic chord-scale relationships for ii–V–I as they might be used in “Tune Up” by Miles Davis (1953).

# Chord-scales and Major Keys

There are many more possible chord-scale relationships beyond those above. The seven notes of the diatonic scale suggest seven basic chord-scale relationships, as summarized in Examples 5 and 6.

Roman numeral Mode Example in C major
Imaj7 Ionian Cmaj7 = C ionian
ii7 Dorian Dm7 = D dorian
iii7 Phrygian Em7 = E phrygian
IVmaj7 Lydian Fmaj7 = F lydian
V7 Mixolydian G7 = G mixolydian
vi7 Aeolian Am7 = A aeolian
viiø7 Locrian Bø7 = B locrian

Example 5. Chord-scale relationships between Roman numerals and modes.

Example 6. Chord-scale relationships for all diatonic harmonies in C.

A similar approach to the one above can be used to derive more chord-scale relationships from the melodic minor, harmonic minor, and harmonic major modes. To learn more about this, consult Further Reading below.

# Applying Chord-Scales to Progressions within a Key

re-organizing these relationships by chord quality reveals the choices listed in Example 7 for matching chord qualities to scales. For example, when improvising on a minor-seventh chord, a musician can choose from three chord-scales: dorian, phrygian, or aeolian (Example 8).

chord quality scale(s)
minor 7th chord dorian, phrygian, aeolian
major 7th chord ionian, lydian
dominant 7th chord mixolydian
half-diminished 7th chord locrian

Example 7. The same chord-scale relationships as in Example 5, rearranged by chord quality.

Example 8. Chord-scale choices for a minor-seventh chord.

However, it’s important to realize that chord-scale theory does not imply that the key modulates each time the chord changes. In other words, these chord-scales are not key centers. Since each mode will imply different extensions, identifying through Roman numeral analysis helps an improviser choose chord-scales that best fit the key center.

For example, the opening measures of “Fly me To The Moon” (1954) contain six of the seven diatonic chord-scale relationships in a circle-of-fifths root movement (Example 9). The chord progression in this example is clearly in the key of C, not seven different keys. Rather than simply coloring each minor chord with a dorian mode and each major chord with an ionian mode, differentiating between the vi and ii chords and between the I and IV chords will result in a more natural-sounding improvised line.

Example 9. These chord-scales applied to “Fly me to the Moon” by Bart Howard (1954) distinguish between different chords of the same quality, because the chords still have different functions.

Example 10 is the a transcription of the first chorus of John Coltrane’s improvised solo on “Giant Steps” (1960), transposed to B♭ for tenor saxophone. Because of the fast tempo and unusual key center relationships, Coltrane improvises melodies that consist mainly of arpeggios and scale fragments. Note how he uses the ionian mode on major chords, the mixolydian mode (with a passing tone between do and te $\hat{1}\ \textup{and}\ \flat\hat{7}$ in m. 9) on dominant-seventh chords, and the dorian mode on minor chords.

Example 10. Transcription of the first chorus of “Giant Steps” by John Coltrane (1960).

# Limitations of Chord-Scale Theory

Some jazz educators have pointed out limitations of the Chord-Scale approach, such as:

• The absence of voice leading between chords. Chord-Scale Theory can lead a student to see each chord as a new key center, instead of viewing an entire chord progression as derived from a parent scale. This can result in choppy, un-melodic improvisation that lacks smooth voice leading between chords.
• Lack of chromaticism commonly used in bebop and blues-based styles. Chord-Scale Theory generally does not account for , , , and employed by bebop musicians such as Charlie Parker, Dizzy Gillespie, and Bud Powell.
• The anachronism of applying a 1960s modal concept to tunes from 1920–50. Louis Armstrong and Charlie Parker did not think in terms of chord-scales. Educators such as Hal Galper and Hal Crook emphasize the importance of melodic embellishment, chord tone improvisation, and blues-based improvisation before delving into chord-scale relationships.
• The avoidance of the oral tradition. Chord-Scale Theory emphasizes the eye and intellect rather than the ear and intuition. Practicing chord-scale relationships does not substitute for transcribing improvised jazz solos, memorizing tunes, improvising along with recordings, or jamming with other musicians as the preferred methods of learning the oral tradition of jazz improvisation.
• Haerle, Dan. 1982. The Jazz Language: A Theory Text for Jazz Composition and Improvisation. Hialeah, FL: Alfred Music.
• Nettles, Barrie, and Richard Graf. 2015. The Chord Scale Theory & Jazz Harmony. Mainz: Alfred Music.
• Russell, George. (1953) 2001. The Lydian Chromatic Concept of Tonal Organization: The Art and Science of Tonal Gravity by George Russell. 4th edition. Brookline, Mass: Concept Pub. Co.
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