Considering the Altered Scale

By: Scott Cook

As guitarists, we have all benefited from moveable chord shapes and scale patterns.

The fact that a single scale pattern, for instance, will retain its structure over a completely new collection of notes by simply sliding up or down the fretboard can be extremely useful, as well as practical in numerous playing situations.

In fact, many guitarists make use of a wide variety of such patterns while improvising melodies without even thinking about what notes they’re playing.

Simply knowing that a given scale pattern corresponds to a given chord type enables those with limited knowledge of the fretboard to produce relatively convincing improvisations.

One such pattern, and the focus of this discussion, is the “altered” scale.

This scale is often used when improvising over dominant-seventh chords—more commonly ones functioning within a minor key.

It’s named “altered” because, when used in its common way (over altered dominant chords), the scale includes all of the possible alterations that you’d find over a dominant chord: b9, #9, b5 (or #11), and b13.

Example 1 shows a complete altered scale being played over an E7#9 chord, which functions as V in the key of A minor.

Example 1: E “altered,” played over a V → i progression in A minor




Click to Hear Example 1


Regarding patterns, the altered scale is the seventh mode of the melodic minor scale.

This means that, as long as you know how to play your melodic minor modes, you can improvise with the altered scale (remember: a mode is simply a rotation of a single scalar collection).

More specifically, when improvising over an E7alt chord, just play the appropriate melodic minor scale and all those alterations that you’re after will be included.

Since the altered scale is the seventh mode of the melodic minor scale, choosing the appropriate one means playing the melodic minor scale whose tonic is a half step above the root of the chord that you’re improvising over.

In Example 1, the notes being played in the first measure correspond to those found in the F melodic minor scale (F, G, Ab, Bb, C, D, E); we’re using this scale since F is a half step above the chord-root, E.

Of course, the role of some of these notes within the given context must be respelled in order to more accurately represent their function.

For instance, Ab (the third note in F melodic minor) is functioning as the third of the underlying E7 chord, which is G#.

Similarly, because G (the second note in F melodic minor) is technically functioning as the #9 over E, it could be spelled as F double-sharp (##).

Therefore, the scale that is played in the first measure of Example 1 could be respelled as: E, F, F##, G#, Bb, C, D.

Examples 2a-b show a couple of lines that make use of the notes from the altered scale over an E7#9 chord, resolving to A minor.

Example 2a: E “altered,” played over a V → i progression in A minor




Click to Hear Example 2a


Example 2b: E “altered,” played over a V → i progression in A minor




Click to Hear Example 2b


Now I’d like to voice a few possible concerns regarding the altered scale, as well as the lines I’ve given in Example 2.

First of all, I have a difficult time justifying what place an F melodic minor scale has in the key of A minor.

Therefore, for those guitar players who want to rely on shapes and patterns exclusively, the F melodic minor scale may not necessarily jump to mind when improvising in A minor.

Secondly, in so far as the literal construction is concerned, the altered scale is incomplete. More specifically, because two of its members are functioning as alterations of a single scale degree (#9 and b9, both functioning as alterations of the second note in the scale), it would appear that the altered scale is missing a member, as shown in Example 3.

Example 3: The altered scale as an incomplete scale



Third, and most notable, the lines given in Example 2 don’t accurately reflect the melodic tendencies of the alterations included in the scale.

It must be understood that alterations, whether applied to a scale or to a chord, are not made without intention.

Therefore, when we alter a note, that alteration should have a purpose—and most often that purpose is a linear, or melodic one. Let’s explore this further.

Examples 4a-c show three chord progressions. In each case, the first chord is an E7 chord that contains alterations found in the altered scale, and the second chord is the chord of resolution, Amin7.

In each of the examples, the most structural members of the first chord are represented using downward facing stems; these are the root, third and seventh of the chord (E, G#, and D, respectively).

The notes with the upward-facing stems are the alterations and their most common resolutions.

Examples 4a-c: E7 with various alterations, resolving to Amin7



In Example 4a, the alterations are the #9 and b9: G and F, respectively.

It is common for these two alterations to appear in succession, in the descending manner shown in the example, and to resolve to the fifth of the next chord.

This creates the melodic line G—F—E. Play through this progression, and listen to the melody created in the uppermost voices.

In Example 4b, the E7 chord contains a b13: C.

This particular alteration functions as a chromatic upper neighbor note.

What is interesting, though, is that it is neighboring the unaltered fifth, B, which is technically not there—at least in so far as the altered scale is concerned.

For this reason, the example shows a resolution to Amin9, which allows the b13 (C) to resolve, as it should, to B. Of course, the B could continue down by step to the root of the chord, and tonic of the key, A.

Finally, in Example 4c, the E7 chord contains a b5 in its uppermost voice: Bb.

Like the b13 in the previous example, this alteration functions as a chromatic upper neighbor, this time to the root of the next chord.

It is, however, possible to think of this note as a chromatic passing tone between an unaltered fifth in the first chord, B, and the root of the second chord, A.

This would result in the melodic line B—Bb—A. Of course, because the unaltered fifth is not included in the altered scale, we can imagine that it’s implied, and go straight to b5.

Following from these common resolutions, we can now see how the lines given in Examples 2a-b contradict the melodic tendencies of the alterations.

For instance, in both cases, Bb (b5) continues at least once upwards through the scale as opposed to resolving downwards to A.

Similarly, in Example 2b, C (b13) moves up to D instead of resolving, as it should, down to B. Also in Example 2b, although the b9 and #9 appear in succession, they continue upwards through the scale instead of resolving (as they would in a chord setting) down to the fifth of the next chord.

In light of these observations, Examples 5a-c give three lines that make use of the specific alterations shown in the progressions of Examples 4a-c, but that resolve in the expected way.

The melody improvised in Example 5a includes the #9 leading to the b9, which resolves to the fifth of Amin7.

The melody improvised in Example 5b includes the b13, which resolves down to the unaltered fifth over E7.

When this note is held over the barline, it becomes the 9th above A, which then continues down by step to the chord-root.

Finally, Example 5c includes the b5. In this example, the raised seventh, G#, is used in combination with b5 to create a chromatic double neighbor to A, the root of the next chord. (Note that Example 5c also includes the b13 resolving, as it should, to the unaltered fifth between the third and fourth notes of measure 1.)

Example 5a: E7 with a #9, b9 resolving to the fifth of the second chord, Amin7 




Click to Hear Example 5a


Example 5b: E7 with a b13 resolving to the unaltered fifth, which becomes the 9th of Amin7



Click to Hear Example 5b



Example 5c: E7 with a b5 resolving to the root of Amin7 



Click to Hear Example 5c


Having a clear understanding of melodic function as it applies to altered notes can help us break away from some of the common shapes and patterns that can, at times, hinder our playing by restricting our ability to move freely about the fretboard.

Notice how, in each of the lines given in Example 5, I’ve used the unaltered fifth over E7, but also managed to get the various “altered scale” alterations in there (Example 5c has both natural 5 and flat 5 in the same measure).

What this shows, most specifically in the fingerings that I’ve used, is that I can retain my sense of A minor (and an A minor scale) across both chords, but still accommodate those altered notes that I feel like incorporating in my improvised melodies.


About the Author

Scott is a Canadian guitarist and educator, currently residing in Vancouver, BC. He holds a PhD in music theory from the University of British Columbia, with research focusing on contemporary jazz.