Could you please explain the real differences between the following three scales natural, melodic and harmonic minors.
The differences are in the notes and scale formula.
Natural: 1 2 b3 4 5 b6 b7
Harmonic: 1 2 b3 4 5 b6 7
Melodic: 1 2 b3 4 5 6 7
I’m guessing that’s not what you’re asking, you want to know why?
The harmonic minor started out to solve a problem with chords in a minor key having a weaker V – I cadence. Without going too in depth with theory, the V-I cadence is the feeling of tension / resolution we hear when we go from a V chord to a I.
Play a I-IV-V, let’s say in C major, the chords are C, F and G.
The V chord (G) has a strong sense of wanting to return to the home key, C. Make it a G7 (V7) and the tension is even stronger.
Try singing “Happy Birthday to You” and at the very end of the song, stop singing right on the word “to”. It feels unsettled if you don’t end on “you”. That’s basically a V-I cadence.
In minor keys, the i-iv-v chords are all minor. In the key of C minor the chords are Cm FM Gm. The V-I in this case is Gm to Cm but it feels a lot weaker than G to C major. Because of this, composers used to often replace the v chord with a V7, in other words swap Gm for G7. Try this sequence and you will see how the pull back to Cm is a lot stronger with G7 as opposed to Gm.
When we do this, our minor scale now has a clashing note when we play the G7. It happens to be the b7 in the scale so we raise it to a major 7 to match the new chord.
That’s basically the reason for the Harmonic minor scale.
The melodic minor come about because of the large interval jump in harmonic minor. b6 to 7 is 3x semitones. Many composers and singers don’t like large interval jumps, either they don’t like the sound or they find them harder to sing. To compensate for this they decided to also raise the b6 in the scale so that there are no intervals more than a whole tone apart.
Hope that makes some sense. 🙂
