Altered Scale

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The seventh mode of the melodic minor scale is known as the altered scale. It is also referred to as the super locrian mode or the diminished whole tone scale. The former name derives from the fact that while the locrian mode flats every degree of the major scale except the fourth:

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The super locrian mode flats the fourth as well:

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The name diminished whole tone comes from the fact that is resembles both the diminished and whole tone scales, to be discussed later.

It is the term altered scale that I prefer, however, because this suggests the most common use for the scale, which is over altered dominant chords. Note that the fourth degree of the scale is enharmonic with a major third:

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Similarly, the third degree is enharmonic with a raised ninth, while the sixth degree is enharmonic with a raised fifth:

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Considered this way, we see that this scale generates a dominant seventh chord with all the common alterations - the flat and sharp ninths and the flat and sharp fifths:

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This scale is thus an ideal choice for use with such chords, which are generally notated either as alt or 7#9#5. The latter notation might appear to be misleading, since it does not specify the flat ninth or flat fifth, but there is no common scale that includes the sharp nine and five without also including the flat versions. In fact, there is no common scale that includes the sharp ninth without including these other alterations as well, so some arrangers use the notation 7#9 to indicate the altered scale, although other arrangers may intend this to suggest the blues scale.

The sound of the altered scale is one of the most complex used in jazz. It may be used over any dominant seventh chord, not just ones that explicitly call for all the alterations. Jazz musicians are always free to make their own alterations.

Note that melodic minor scale contains three modes that can be appropriate to used over dominant seventh chords - the lydian dominant scale, the fifth mode, and the altered scale. The lydian dominant scale and the altered scale are built on root a tritone apart:

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Thus, whenever one is using the altered scale, one could also consider this as the lydian dominant scale of the chord a tritone away. This is another reason tritone substitutions work so well.

Copyright 2000 Outside Shore Music
Authored by Marc Sabatella

Altered Scale