Generally, an altered scale (also known as altered dominant scale or super Locrian mode) is a seven note scale with a numeric formula of 1-♭2-♭3-♭4-♭5-♭6-♭7-8/1 however, it is sometimes written with two second and two fifth degrees minus a fourth and sixth, this is done to highlight the altered tones in both the scale and chord. The altered scale is also the seventh mode of the melodic minor scale.
When a functioning dominant chord has an altered tone (like a ♭9, ♯9, ♭5 or ♯5), we need a scale that compliments these alterations, this is where the altered scale comes in. When playing a functioning dominant chord with an alteration, say for instance C7(♯5♭9), playing a C altered scale over this chord would highlight the ♯5 and ♭9 because the altered scale contains both of these notes, the ♭2 being enharmonic to a ♭9 and the ♭6 enharmonic to a ♯5.
Altered scale profile
|Notation formula (key of C)||C-D♭-E♭-F♭(E)-G♭-A♭-B♭-C/1|
|Stepping||half, whole, half, whole, whole, whole, whole|
|Tonal||semi-tone, tone, semi-tone, tone, tone, tone, tone|
|Harmonized triads (key of C)||C⁰ / D♭mi / E♭mi / F♭⁺(E) / G♭ / A♭ / B♭⁰|
|Harmonized tetrads (key of C)||Cmi7(♭5) / D♭mi(MA7) / E♭mi7 / F♭MA7(♯5) / G♭7 / A♭7 / B♭mi7(♭5)|
Altered scale patterns
Altered scale audio sample(s)
|C Altered scale pattern #4|