Understanding the Harmonic Minor

Now, let's untangle when exactly the Harmonic Minor Scale comes into play.

As mentioned previously, the only difference between the Natural Minor and Harmonic Minor Scales is the 7th.

The Natural Minor contains a Minor 7th interval, while the Harmonic Minor uses a Major 7th.

While this Scale can absolutely be treated as the primary backbone of a song, when it is used in a temporary context, by far the most common usage of it is to build a Dominant 7th chord off of the 5th Scale Degree.

This allows you to resolve from a V back to a i.

Typically when this happens, the melody and/or improvisation over top will need to temporary switch to Harmonic Minor as well (by simply sharping the 7th note), but if the 7th is not being played, then there will be no need to change scales at all!

This will be one of the most common instances of "scale-swapping" you will encounter, so it's good to try and get your head around it early on.