This chapter discusses methods for altering chord progressions through chord substitution.
- A progression that moves by fifth can substitute the first chord with the dominant chord that shares the same root. This makes the first chord an applied chord to the second chord.
- Mode mixture is when a piece in a major key use chords borrowed from the parallel minor key (or vice-versa, though this is less common).
- In jazz, the most common mixture chords are substituting iiø7 for ii7 and adding♭9 to a V7 chord.
- The most common mixture chords, including iiø7 and V7♭9, substitute for the regular .
- Tritone substitutions replace dominant chords with another dominant chord a tritone away. The name refers to the fact that the substituted chord is a tritone away from the original chord, and also that the two chords share a tritone.
Creating new interpretations of old favorite tunes is one of the cornerstones of jazz, and because of this, the concept of chord substitutions is extremely important. Substitutions provide a way for performers and arrangers to put a new spin on more well-trod harmonic progressions. This chapter uses the as a basic progression to be altered, but these substitutions can be applied anywhere in a harmonic progression.
As discussed in the Applied Chords chapter, applied chords can be productively related to the diatonic chord with which it shares a root note.
Because by 5th is extremely common in jazz, there are many opportunities for performers to simply substitute the first chord in a fifth-wise chord progression with the dominant 7th built on the same root. One especially common place where this is implemented is in the turnaround, where, because each chord is related to the next by fifth, a chain of applied V7s is a common variant ().
“All of You” by Cole Porter is a composition that has mode mixture built into it. Listen to this recording by Ella Fitzgerald (transcribed in ), conveniently in C major, and observe how the alternation between A♮ () and A♭ () creates catches the ear and imbues a sense of sentimentality in the song. A♭ here can be understood as being borrowed from the parallel minor (C minor), a practice known as .
Many songs, like “All of You,” have mixture built into their chord structure. But mixture chords can also work as improvised substitutions: a chord within a diatonic chord progression can be substituted with its minor-mode variant to produce a color change that won’t change the overall function of the chord. A mixture substitution works best when the scale degree being inflected is , and is therefore being transformed into . As an example, consider the turnaround in: instead of a diatonic version, one may choose to incorporate scale-degree ♭6 to generate some more colorful harmonies. These particular substitutions—changing a ii7 to a iiø7, and a G7 to a G7♭9—are particularly common uses of mode mixture in jazz.
While the above methods of substitution are common in pop and classical styles as well, the tritone substitution is unique to jazz. Tritone subs take the place of V7 chords, either applied or diatonic. The “tritone” part of the name comes from two ways in which tritones are important in these substitutions:
- The substituted chord is a tritone away from the chord it is replacing, and
- The chords are related because they share the same tritone.
Why this is true is best explained graphically, as in: because the tritone evenly divides the 12-tone collection, transposing by tritone maps the tritone onto itself. Speaking practically, the bottom line is that any dominant seventh chord can be replaced by the dominant seventh chord a tritone away, and the progression still functions the same way.
shows how tritone substitutions are commonly used in the turnaround.
- As discussed above, it’s common to replace the diatonic chords with applied chords that share the same root, yielding a progression consisting entirely of V7 chords—this is shown in the right-hand harmonization on the top row.
- From there, tritone substitutions can be used for any V7 chord.
- Most commonly, every other chord is replaced with a tritone sub, yielding a chromatic bass line and smooth voice leading, as in the bottom row of harmonizations.
The ii–V–I chapter visualized the ii–V–I schema within a voice leading space constructed by Michael McClimon (2017). McClimon further visualizes the tritone substitution as a kind of shadowing space behind the typical ii–V space ( ). Click here to view his animation of the progression of “Blues for Alice” and its movement through the ii–V space with tritone substitutions. Notice that the tritone-substituted V7 chord is preceded by its ii7 chord, and that both chords are in the green space that McClimon places behind the foreground ii–V space.
As with embellishing chords, substitutions are not always represented the same way in a lead sheet.
- There may not be any substitution notated, and instead the performers are improvising this addition as they play.
- The substitution may be built into the chord progression and thus be notated in the lead sheet symbols.
- The substitution may be indicated as an alternate harmonization, and shown in lead sheet symbols with parentheses around the substituted chords.
This is illustrated in, with different ways of showing a modally-mixed iiø7 chord in “Satin Doll” by Duke Ellington.
Substitutions can be improvised and not notated in the score at all (a), written directly into the lead sheet symbols (b), or written in parentheses to indicate that the substitution is optional (c).
- Levine, Mark. 1995. The Jazz Theory Book. Petaluma, CA: Sher Music.
- McClimon, Michael. 2017. “Transformations in Tonal Jazz: Ii–V Space.” Music Theory Online 23 (1). http://mtosmt.org/issues/mto.17.23.1/mto.17.23.1.mcclimon.html.
- Bebop composition (.pdf, .docx). Asks students to build on knowledge of swing rhythms, ii–V–I, embellishing chords, and substitutions to create a composition in a bebop style.
- Clock face visualization © Megan Lavengood is licensed under a CC BY-SA (Attribution ShareAlike) license
- McClimon Figure 10
Broadly speaking, a turnaround is the use of a non-tonic chord (usually dominant) at the end of a harmonically closed unit to transition into the beginning of the following on-tonic unit. In jazz, the term "turnaround" often refers to the progression vi–ii–V–I. The exact qualities of these chords is highly variable, and one or more of the chords may be substituted with a different, related chord.
The distance between roots (NB: not basses!) of adjacent chords. For example, "root motion by step" refers to the distance between two chords that are only one step apart, such as I and ii, IV and V, etc.
The intermixing of major and minor versions of scale-degrees 3, 6, and/or 7 within a composition.