Harmonic minor scales

To review:

A major scale has a specific whole and half step pattern. The major scale has half steps between scale degree 3-4 and 7-8.

We can start a scale on any note of the major scale getting the modes. One mode that is commonly used is the Aeolian mode, also known as the Natural minor scale. The natural minor scale has half steps between 2-3 and 5-6.

Relative major and minor scales: scales that have the same key signature but different starting notes. The relative minor starts on scale degree 6 of major.
C major and A minor are relative major and minor scales.

Parallel major and minor scales: major and minor scales that have the same starting note but have different key signatures (i.e., they have different pitches).
C major and C minor are parallel major and minor scales.

Harmonic Minor

The natural minor scale has a unique sound since it does not have a half step between the 7 and 8 scale degree; there is no leading tone (scale degree 7 half step from 1 or tonic). Not having a leading tone means that the key defining progression, a I-V-I (in the key of C = C-G-C), will not sound very convincing.

To make this progression sound more convincing, the 7th scale degree of a natural minor scale is raised, making the 7th scale degree a half step from 1/tonic and giving the V chord more tension; it now wants to lead back to the tonic.

The harmonic minor scale gets its name from the fact that it fixes the harmonies.

Therefore, the harmonic minor scale has half steps between 2-3, 5-6 and 7-8.
The interval between the 6 and 7 scale degree is a whole+half step and gives the scale its unique sound.

We will diagram the harmonic minor scale as follows:

The chord that comes from this scale ( C Eb G B) is a minor-major 7th chord – a very unusual 7th chord.