Piano Forum

Perhaps the topic here can be clarified by providing the practical rationale for having different minor scales in the first place instead of simply applying a formula to get the proper notes.

The first concept to grasp is that there are two “classes” of minor scales: Parallel and Relative. The parallel is the method by which the tonic note remains the same and notes within the major scale are altered to become whatever minor scale is desired. In other words, the key center is fixed and the key signature changes. In the Relative variety, the opposite occurs. Here, the key signature remains the same, but the key center changes.

The easiest thing to begin with is C major since it (and the relative minor) are all white notes. The relative minor is simply a “mode” within each key signature that has all of the same notes as the major key, just with a different starting point. In the case of this key, the relative minor occurs on ‘A’ or the sixth of the major scale. Keep the same notes as C major, but play from A to A using that key. This scale occurs “naturally” within the key of C major, hence being dubbed the “natural minor.” If you compare the A minor scale with its Parallel major, you’ll notice that the 3rd, 6th, and 7th have been lowered by one half-step each. You can do the same with C major. It’s Parallel would lower the same scale degrees to become Eb, Ab, and Bb.

Now, the natural scale has its uses with regards to both melody and harmony, but over the course of several hundred years as music transitioned from the Middle Ages to the Baroque, composers realized that certain alterations to minor keys “sounded” better under specific circumstances, which is why there are several types within each class of minor mode. Natural has already been discussed above.

The Melodic variety of minor exists because within the modern tonal system (ca. Renaissance onwards) composers realized that when a melody within a minor key ascends, it sounds more complete if the top half of the minor scale RAISES the 6th and 7th as it approaches the tonic note. For example, in the key of A minor, an ascending melody through the top of the scale would sound more “finalized” or “complete” if F and G were raised back to F# and G# as if it were in the major mode. It very much strengthens the return to A as the key center due to that half-step between the G# and the A. If the melody is descending within a minor key, composers noticed that the same effect occurs as the melody approaches the other most important note within a key in common practice tonality, which is the Dominant, or 5th scale degree of the key. In our key of A minor, descending through G and F to the E (the dominant of A) strengthens the tonal approach to the dominant note with the same order of whole- and half-steps. Notice that in the ascending version of the scale, the trajectory of the notes creates a whole-whole-half order of steps (E, F#, G#, A). The same occurs in the descending trajectory. A, G, F, E is once again whole-whole-half, making the final half step to the dominant E sound more “complete.”

The Harmonic minor scale is useful in that it has practical effects regarding the “harmonies” that occur within a minor scale. In the Natural minor, notice that all of the primary chords (I, IV, and V) that are often used to establish a key are now MINOR as opposed to all being MAJOR when the key is itself major. The harmonic minor scale keeps the 7th scale degree raised, and is done so for one purpose only: that is to keep the V chord MAJOR, thus preserving that important half-step between the 7th and tonic. Preserving the other notes of the minor scale would render the I and the IV as still minor in chord quality, which would help retain the overall minor sound within the key. Composers realized that a minor V chord just sounded incomplete when used in a cadence to the tonic, so simply raising that 7th scale degree when required solved the tonal problem.

My suggestion for developing a full understanding of all this is to play tetrachord scales in a few keys and drill the process by which you would achieve all the different types of minor scale within a particular key. The tetrachord scale is done with two hands and not using the thumbs. In the key of C major, LH 5-4-3-2 are on C-D-E-F, and RH 2-3-4-5 will be placed on G-A-B-C. Play the major scale upwards and then back down, from there:

1. Move your hand position to the 6th scale degree, in this case A to A but retaining the C major key signature (all white notes).
2. Play the natural minor scale up then down.
3. Play the ascending melodic minor scale by raising the 6th and 7th (F# and G#).
4. Play the descending melodic minor scale by reverting back to F and G.
5. Play the ascending harmonic minor scale by raising only the 7th to G#. After this, play the scale with the RH and then play the primary chords to hear the effect. A-B-C will get the a-minor (i) chord, D-E-F will get d-minor (iv), and G# will get E major (V), then cadence on a-minor upon reaching the top A.
6. Go back to C major and do the same steps with the Parallel (by lowering the 3rd, 6th, and 7th scale degrees).
7. Apply these steps to all other keys.

To ensure you are correct, have a circle of fifths chart handy that has both major and minor keys represented so you can begin to internalize all of the “relative” relationships between the keys. Remember to shift your hand position to the 6th scale degree within the key you are working on while retaining the same notes as the major. Once you master all of these, you can move on to all the different “modes” within a major key by exploring all of the different starting points on the individual scale degrees. For example, D to D, E to E, etc using the key of C major. You’ll begin to see that the characteristics of each mode is determined by where in the scale the half-steps reside.

Hope this helps!