Altered Chords

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One of the unique features of jazz harmony is its use of complex chords. In addition to the diatonic chord extensions discussed in the previous section, jazz musicians often alter these chords by raising or lowering some of the pitches a half step. This usually does not change the function of the chord, but it adds harmonic color.

The most important notes in a chord are the root, which is obviously the key to determining function, and the third and seventh, which together determine the quality of the chord - major, minor, or dominant. Altering any of these pitches results in a fundamentally different chord. For example, lowering the third of a dominant seventh results in a minor seventh:

[EXAMPLE]

Thus, this would be more properly considered a substitution of a different chord than an alteration. When jazz musicians speak of alterations, they are referring to alterations of the fifth, ninth, eleventh, or thirteenth.

By far the richest set of alterations are performed on the dominant seventh chords. These alterations create additional tension that can be released by the resolution to the tonic. We will consider the possible alterations one at a time, then discuss some common combinations of alterations.

Lowering the fifth of a dominant seventh chord results in a chord that is notated 7b5, or sometimes 7-5:

[EXAMPLE]

This chord became especially popular, and controversial, during the bebop era.

Raising the fifth results in a chord that may be notated 7#5, 7+5, 7+, or 7aug, since the triad at the root of the chord is now an augmented triad:

[EXAMPLE]

While both these alterations change the quality of the underlying triad, the chords still serve a dominant function:

[EXAMPLE]

Note that altering the fifth does not in itself imply anything about the ninth or higher extensions. In the absence of explicit alterations to the extensions, they may be assumed to be diatonic. For example, a 9b5 chord would be:

[EXAMPLE]

The ninth can be lowered or raised as well. A dominant seventh chord with a lowered ninth is notated 7b9 and looks like this:

[EXAMPLE]

A 7#9 chord looks like this:

[EXAMPLE]

While both of these chord can still serve a dominant function, the 7#9 chord is often used as a tonic chord as well, particularly in blues:

[EXAMPLE]

Note that the raised ninth is enharmonic with a minor third:

[EXAMPLE]

Earlier it was observed that a blue third might lie somewhere between the major and minor third. The 7#9 chord, having both of these thirds, then serves as an approximation of this blue third. Blues progressions are often notated with an unaltered dominant as the tonic, but it is generally understood that since it is a blues, the raised ninth may be included as well.

Turning now to the eleventh, we see that raising it produces a note that is enharmonic with the lowered fifth, so the resulting 7#11 chord is similar to the 7b5 chord, or more particularly, to the 9b5 chord:

[EXAMPLE]

Note the primary difference between the 7#11 chord and the 9b5 chord is that the former explicitly contains a natural fifth as well as the raised eleventh or lowered fifth. This has ramifications on the choice of scale to be used over the chord. However, it should be mentioned that many arrangers do not observe this distinction, so you are largely on your own in determining which is intended when reading an arrangement. This is no big deal; jazz musicians commonly perform their own alterations anyhow.

Note also that by altering the eleventh, the resulting chord is not as dissonant as the unaltered dominant eleventh chord:

[EXAMPLE]

Lowering the eleventh produces a note that is enharmonic with the major third which is already present in the chord:

[EXAMPLE]

This particular alteration is therefore not very interesting and will not be considered further.

Lowering the thirteenth produces a note that is enharmonic with the raised fifth, so the resulting 7b13 chord is similar to the 7#5 chord:

[EXAMPLE]

Since the 7b13 chord, by implication, contains an eleventh, this chord is rather dissonant if the diatonic eleventh is used. It is not always clear what an arranger might have in mind when specifying this chord. Presumably they are trying to specify that the natural fifth is to be used in addition to the lowered thirteenth or raised fifth.

Raising the thirteenth produces a note that is enharmonic with the minor seventh which is already present in the chord:

[EXAMPLE]

This alteration will therefore not be considered further.

The alterations of the fifth and ninth are often combined to produce even richer harmonies. One of the most common combinations is the 7b9b5 chord:

[EXAMPLE]

Note that the third, flat fifth, seventh, and flat ninth of this chord form a dominant seventh chord a tritone away from the original root:

[EXAMPLE]

The root of the original chord becomes a sharp eleventh in the chord a tritone away:

[EXAMPLE]

This is why tritone substitutions work so well - when we make a tritone substitution, such as Db7 for G7, we are really just adding a flat fifth and flat ninth, which adds color without altering function.

It is possible to include both the lowered and raised version of the same note in the same chord. For instance, a 7#9b9 chord would have both a lowered and raised ninth:

[EXAMPLE]

The chord that includes all four of these alterations is actually quite common, and is often referred to simply as the altered chord, notated 7alt:

[EXAMPLE]

This chord is also notated 7#9#5; the b9 and b5 are understood because they are present anyhow in the scale most commonly associated with the chord. Since jazz musicians generally associate chords with scales, chord names are usually chosen to make this association as obvious and direct as possible. Thus, in practice, completely specifying all alterations in a chord is not normally necessary, since one or two are almost always enough to imply a particular scale. This will be discussed further in the chapter on scales.

While it is possible to alter the fifths, ninths, elevenths, and thirteenths of the major and minor families seventh chords, jazz musicians tend to use only those alterations that suggest common scales. So only those alterations will be presented here. It should be clear how to generate any of the other possible alterations if the need ever arises.

There are two common alterations performed on major seventh chords. The first is the maj7#11:

[EXAMPLE]

This chord serves the tonic function. However, note that this is the chord that is obtained by building diatonically on the fourth degree of the scale:

[EXAMPLE]

Therefore, this chord is commonly used in subdominant situations, even when the alteration is not explicitly specified:

[EXAMPLE]

The other common altered major chord is the maj7#5:

[EXAMPLE]

The scale normally associated with this chord also contains a raised fourth, so the chord is sometimes notated maj7#11#5:

[EXAMPLE]

Note that, regardless of the spelling, this chord contains an augmented triad at its root, and may therefore be notated maj7aug or maj7+. It usually serves a tonic function:

[EXAMPLE]

There are three common alterations commonly performed on minor seventh chords. The first is the m7b13, which is also notated m7b6:

[EXAMPLE]

The second common alteration is the m7b9:

[EXAMPLE]

The third is the m7b5, which is actually just another name for the half-diminished chord:

[EXAMPLE]

The tonic minor chord is rarely altered. It already has a fairly exotic sound due to the augmented triad on top:

[EXAMPLE]

Note that, as was suggested in the previous section, the augmented and half-diminished chords have been covered as alterations to the major, minor, and dominant families. The fully diminished seventh chord is not normally extended or altered.

Copyright 2000 Outside Shore Music
Authored by Marc Sabatella

Altered Chords