When I was learning scales the altered scale was always sort of an enigma, possibly because of its ominous name or unfamiliar shape to me. I always feel slightly irked when certain scales are referred to as ‘exotic’ as the altered scale sometimes is (wrongly, in my opinion).
Common in jazz, but also pop and in some more modern classical and Romantic period music, the altered scale is a mode of the melodic minor (modes will be covered later – definitely worth getting up to speed if you’re not). Its sound is dominant, as it contains major third and flattened seventh degrees, however the rest of the degrees are all altered.
The melodic minor is really two scales with ascending and descending variations, but for simplicity I’ll nearly always be referring to the ascending version. Check out what I mean here.
Certain people apparently refer to it as the ‘Super-Locrian mode’ or some waffle but I’ve not met any of them and, seeing as the Locrian mode is painfully difficult to compose with, the altered seems more befitting to me.
To understand why it’s called ‘altered’ is really quite simple, but first let’s look at a simple C major scale:
This contains the notes C, D, E, F, G, A, B and C. Each degree is of the scale is ‘natural’ when our key signature is C major (no sharps or flats). In contrast, the altered scale literally ‘alters’ each degree by flattening it:
This contains the notes C, Db, Eb, Fb, Gb, Ab, Bb and C (fig.1) however some might prefer to understand this as C, Db, D#, E, F#, G#, Bb and C (fig. 2).
Fig. 1 is how the scale reads enharmonically (read up on enharmonic equivalents here), but fig. 2 is how I tend to remember the degrees. What’s really important is what’s easier for you to understand the scale. [However, if you’re in an exam it’s more important to understand what’s technically correct, which is fig. 1!]
In the example of C, an easy way to get your fingers around the scale is just playing a B major scale, with the Bs replaced with Cs. The tones are as follows, with the alternatives in brackets:
Flat 3rd (or minor 3rd)
Flat 4th (or major 3rd)
Flat 5th (or sharp 4th, commonly referred to as sharp 11).
Flat 6th (or sharp 5th)
How to Use the Scale
The altered scale is most commonly used over a V chord leading to the I. For example, using a ii, V, I chord progression in the key of C major (D-, G7, C) the G altered scale would be used over the G7 chord.
Some chords that can be extrapolated from the scale are below:
In fig. 3, the chord is could be looked at as a C7 shell (C, E, Bb) with a Db (b9) and F# (#11) on top of it. Another way to understand this would be C and E at the bottom of the chord with an F# 1st inversion chord in the top of the chord (A#, C#, F#).
In fig. 4, chord is a C+7(#9) which contains both an E and D# making it technically neither major nor minor. The Bb, Eb and G# is a series of fourths; if your hand can reach, the next fourth up would be the Db.
Finally in fig. 5, I would describe this this chord as an F#/C . Notice it contains the same notes as our first chord, how you would write it would depend on context and function; e.g as a V in F minor, I would write C7(b9, #11), however as a V in B or B minor, F#/C would make more sense.
Unless there is a specific need for a particular voicing (like an F# in the melody or a combination of notes that gives the correct chordal colour) then we often see ‘C alt.’ written, giving the accompanist the option to choose their own voicing. Often when transcribing in a rehearsal or writing environment I too will use C alt for speed but it’s entirely down to you what you write.
The altered scale can function as a great starting point for writing or soloing over dominant chords in major or minor keys. In addition, if you’re confronted by a chord with any of these extensions in, the altered scale is a handy mode to turn to and can add great sophistication and interest and when composing, the chord oozes tension and works well as a standard V chord.
I’d be interested to hear your thoughts or answer any questions.