Jazz Harmony
Jazz harmony connects seventh chords through guide tones, especially thirds and sevenths. Extensions add color, substitutions create new bass routes and ii-V-I progressions organize motion toward a temporary or final tonic.
- seventh chords as a starting point
- thirds and sevenths guide motion
- ii-V-I is the core route
What makes jazz harmony different?
Jazz commonly treats seventh chords as basic sonorities. Ninths, elevenths and thirteenths extend them, while altered fifths and ninths intensify dominant motion.
The chord symbol supplies options, not one fixed voicing. Register, melody, bass and ensemble role determine which notes a player includes.
How does ii-V-I work?
Dm7: predominant. D-F-A-C prepares the dominant.
G7: dominant. G-B-D-F contains the tritone B-F.
Cmaj7: tonic. C-E-G-B supplies the destination.
The guide tones move efficiently: C in Dm7 falls to B in G7, and F in G7 falls to E in Cmaj7. Common tones can remain fixed.
Which chord tones matter most?
The third establishes major or minor quality. The seventh distinguishes maj7, dominant 7 and minor 7 structures. Altered tones state the intended tension.
The root can be supplied by the bassist, and an unaltered fifth can often be omitted. Good voicing begins with function and voice leading before adding every written extension.
What is a tritone substitution?
Replace G7 with D-flat7 before C. G7 contains B-F; D-flat7 contains F-C flat, and C flat sounds as B in equal temperament.
The essential tritone remains while the bass moves D-D flat-C in a chromatic line. Altered extensions and melody determine which version fits.
What other substitutions are common?
| Technique | Example in C | What remains |
|---|---|---|
| Diatonic substitution | Am7 for Cmaj7 | shared tonic-area tones |
| Secondary dominant | A7 before Dm7 | targeted dominant motion |
| Backdoor cadence | Fm7-B-flat7-Cmaj7 | borrowed predominant and flat-VII dominant color |
| Diminished passing chord | Cmaj7-C-sharp dim7-Dm7 | chromatic bass and common tones |
A substitution should preserve a useful function, melody note or voice-leading route. Similar chord shape alone is not enough.
How do you read extensions?
Build upward in thirds: 1-3-5-7-9-11-13. Extensions use the same letter names as scale degrees beyond the octave.
A C13 symbol does not require seven simultaneous notes. A practical voicing may use C, E, B flat and A, leaving the fifth and some lower extensions out.
How should you practice jazz harmony?
- Play shellsuse root, third and seventh for ii-V-I.
- Follow guide tonessing C-B-B and F-F-E through Dm7-G7-Cmaj7.
- Add one extensioncompare G7, G9 and G13.
- Substitute the dominantcompare Dm7-G7-Cmaj7 with Dm7-D-flat7-Cmaj7.