Chord substitutions are an essential aspect of jazz improvisation. They allow jazz musicians to add color and interest to their playing by replacing standard chord progressions with alternate harmonies. The following are some of the most commonly used chord substitutions in jazz improvisation:
Dominant 7th Substitutions: Dominant 7th chords can be substituted with other dominant 7th chords that are a fifth apart. For example, a C7 chord can be substituted with a G7 chord.
Tritone Substitutions: Tritone substitutions involve replacing a dominant 7th chord with another dominant 7th chord that is a tritone (augmented fourth) away. For example, a C7 chord can be substituted with an F#7 chord.
ii-V Substitutions: A ii-V substitution involves replacing a ii chord with a V chord. For example, a Dm7 chord can be substituted with a G7 chord.
Altered Dominant Substitutions: Altered dominant chords are dominant 7th chords with altered extensions such as raised or lowered 9th, 11th, or 13th notes. These chords can be used to substitute for dominant 7th chords.
Cycle of Fourths Substitutions: The cycle of fourths is a musical concept where chords are played in a sequence of fourths. In jazz, this concept is often used as a chord substitution, where a chord progression is played in a cycle of fourths rather than in its original key.
It is important to note that chord substitutions should be used tastefully and with intention. Overuse of chord substitutions can lead to a cluttered and discordant sound. Additionally, the use of chord substitutions should enhance the overall musicality of a piece and not detract from it.
In conclusion, chord substitutions are an important aspect of jazz improvisation that allow musicians to add interest and color to their playing. The aforementioned substitutions are some of the most commonly used, but there are many others as well. The key to effective chord substitution is to use them tastefully and with intention to enhance the overall musicality of a piece.
Source: "Jazz Theory and Practice" by Richard Small and Jeff Hellmer.