Table of Contents
Rhythm changes are a fundamental harmonic progression in jazz and popular music, originating from the chord changes of George Gershwin’s “I Got Rhythm.” Traditionally, these progressions follow a predictable pattern based on diatonic chords within a key. However, incorporating non-diatonic chords can add color, tension, and interest to musical arrangements, making them more dynamic and expressive.
Understanding Rhythm Changes
Rhythm changes typically consist of a 32-bar form that features a series of chord progressions rooted in the key of the tune. The standard progression often includes:
- I – vi – ii – V chords
- Repeated sections with variations
- Bridge section often shifting to a different key or mode
These progressions form the harmonic backbone for countless jazz standards and improvisations, providing a familiar framework for musicians.
What Are Non-Diatonic Chords?
Non-diatonic chords are chords that do not belong to the diatonic scale of the key in which the piece is written. They introduce chromaticism and unexpected harmonic shifts, creating tension or color. Common types include:
- Borrowed chords from other keys or modes
- Chromatic passing chords
- Altered chords with flattened or sharpened tones
Incorporating Non-Diatonic Chords into Rhythm Changes
Adding non-diatonic chords into rhythm changes can enhance harmonic interest. Here are some approaches:
Using Borrowed Chords
Borrow chords from parallel modes or keys. For example, borrowing a bVII chord from the Mixolydian mode can add a bluesy feel:
Example: replacing the V chord with a bVII chord before resolving back to I.
Chromatic Passing Chords
Insert chromatic passing chords between diatonic chords to smooth transitions or create tension. For example, adding a chromatic approach to the V chord:
From I to V: I – chromatic approach – V.
Altered Chords
Use altered chords such as b9, #9, #11, b13 to add dissonance and color, especially over dominant chords. These are common in jazz improvisation.
Practical Examples
Consider replacing the standard V chord in rhythm changes with a bII7 (a tritone substitution) for a richer sound:
Original: I – vi – ii – V
Modified: I – vi – ii – bII7 – I
This substitution introduces a non-diatonic dominant that creates a smooth, chromatic bass line and harmonic interest.
Conclusion
Incorporating non-diatonic chords into rhythm changes opens up a wide array of harmonic possibilities. It allows musicians to craft more expressive, colorful arrangements and improvisations. By understanding and experimenting with borrowed chords, chromatic passing tones, and altered chords, composers and performers can elevate their harmonic language and create memorable musical moments.