Minor Scales - Melodic and Harmonic Minor
The melodic and harmonic minor scales occur when the natural minor scale is altered to improve melodic movement or to make additional harmonies available.
Melodic Minor Scale
The melodic minor scale is unique because it is different going up (ascending) than it is going down (descending). The ascending melodic minor scale has a raised 6th and 7th scale degree. The 7th degree is raised by a half step to make the interval between it and the tonic into a half step, which creates a stronger melodic pull towards the tonic. When it is raised in this way, the 7th scale degree of a minor scale is called the leading tone instead of the subtonic. The submediant (6th degree) is raised because otherwise the interval between scale degrees 6 and 7 would be a minor third rather than a whole or half step, which might make a melody sound disjointed. Descending, the melodic minor scale is identical to the natural minor scale because the need to create drive upwards (ascending) to the tonic is not necessary when a melody is descending.
|A natural minor:||A||B||C||D||E||F||G||A||G||F||E||D||C||B||A|
|A melodic minor:||A||B||C||D||E||F-sharp||G-sharp||A||G||F||E||D||C||B||A|
A Melodic Minor Scale
Harmonic Minor Scale
The harmonic minor scale comes from composers raising the 7th scale degree in order to have all the pitches needed for the most common and important harmonies. By raising the 7th degree, the quality of the chords built on the 5th and 7th scale degrees is changed, resulting in a major V chord and a diminished vii° chord, which are very useful chords in harmonic progressions because they both have a strong drive towards the tonic chord. Raising the 7th scale degree also changes the chord built on the 3rd scale degree from minor (iii) to major (III), but III is not used as often as V and vii°. Because it is used for harmony rather than melody, the minor 3rd created between the 6th and 7th scale degrees is not avoided as in the melodic minor scale (above). See Chords for more information about chord qualities and Chord Analysis - Roman Numerals for more about the harmonic analysis below.
|A natural minor:||A||B||C||D||E||F||G||A|
|A harmonic minor:||A||B||C||D||E||F||G-sharp||A|