Why The Ascending Form Of The Melodic Minor Scale Differs From Its Descending Form

If you want to know why the ascending form of the melodic minor scale differs from its descending form, then this lesson is for you!.

Most scales on the piano have an ascending form that is related to the descending form. The only difference between both may just be the order of the notes. For example, the C major scale:

…ascends from C:

…to C:

…and descends from C:

…to C:

I’ll be explaining why the ascending form of the melodic minor scale differs from its descending form, but before we do that, let’s do a review on the melodic minor scale.

A Note On The Melodic Minor Scale

Every key (whether major or minor) has its traditional scale. The traditional scale of a key gives you an outline of the notes in that key. The traditional scale of the major key is the natural major scale, while that of the minor key is the natural minor scale.

The natural minor scale has two chromatic variants – the harmonic minor and the melodic minor scales. Simply put, the melodic minor scale is a chromatic variant of the natural minor scale.

The term chromatic is used to describe an idea (be it a note, scale, interval, chord, or chord progression) that is foreign to a given key.

The A natural minor scale:

…is the traditional scale of the key of A minor, hence, it outlines all the notes in the key of A minor.

The A melodic minor scale:

…contains a modification of the sixth and seventh tones from F and G:

…to F# and G#):

…which are foreign to the key of A minor.

In a nutshell, the melodic minor scale is a natural minor scale modified with chromatic or foreign notes.

“Before We Proceed, Why Is It Called The Melodic Minor Scale?”

The melodic minor scale was derived from the harmonic minor scale (another chromatic variant of the natural minor scale) which is formed by raising the seventh degree of the natural minor scale by a half step

Raising the seventh tone of the A natural minor scale:

…which is G:

…by a half step (to G#):

…produces the A harmonic minor scale:

The A harmonic minor scale:

…is a gapped scale that has a dissonant melodic interval between its sixth and seventh tones (F and G#):

The interval from the sixth degree of the A harmonic minor scale (which is F):

…to its seventh degree (which is G#):

…is an augmented second interval.

The augmented second interval between the sixth and seventh tones of the harmonic minor scale sounded harsh, and constituted a melodic problem. (If you are from a classical background, you’ll probably remember that all augmented and diminished intervals are dissonant.)

In a bid to solve the melodic problem of the harmonic minor scale, the sixth degree of the harmonic minor scale (which is F):

…was raised by a half step (to F#):

…to form another chromatic variant (of the natural minor scale):

…named after the melodic problem it solved, hence, the name melodic minor scale.

“In A Nutshell…”

The melodic minor scale can be considered as a natural minor scale with its sixth and seventh degrees raised by a half step. The A melodic minor scale:

…is a natural minor scale:
that its sixth and seventh degrees (F and G):

…are raised by a half step (to F# and G#):

“For Your Reference, Here’s The Melodic Minor Scale In All Twelve Keys…”
C melodic minor scale:

C# melodic minor scale:

D melodic minor scale:

Eb melodic minor scale:

E melodic minor scale:

F melodic minor scale:

F# melodic minor scale:

G melodic minor scale:

Ab melodic minor scale:

A melodic minor scale:

Bb melodic minor scale:

B melodic minor scale:

To take you to the next level in this lesson, let’s divide the melodic minor scale into two equal parts (aka – “tetrachord”.)

The Upper And Lower Tetrachords Of The Melodic Minor Scale

Tetrachord comes from two Greek words – tetra and chord. Tetra means four while chord means notes. Violin players are familiar with the tetrachord because they play all the notes of the major scale using only two strings – four notes per string.

Every traditional scale can be broken down into two tetrachords (four notes per string), the lower and upper tetrachords. On the piano, the first four notes of a scale is the lower tetrachord while the last four notes belong to the upper tetrachord.

In the A melodic minor scale:

…the lower tetrachord consists of A, B, C, and D:

…a set of four notes, while the upper tetrachord consists of E, F#, G#, and A:

So, the A melodic minor scale:

…can be broken down into its lower tetrachord:

…and upper tetrachord:

…respectively.

“A Contrast Between The Upper Tetrachords Of The Natural Major And Melodic Minor Scales…”

Let’s take a look at the lower and upper tetrachords of the A natural major scale:

The lower tetrachord consists of A, B, C#, and D:

..while the upper tetrachord consists of E, F#, G# and A:

Due to the fact that the upper tetrachord of the A natural major scale:

…and the upper tetrachord of the A melodic minor scale:

…are identical, playing the first four notes (tetrachord) in the descending form of the A melodic minor scale which are A:

…G#:

…F#:

…and E:

…sounds like we are playing the descending form of the A natural major scale.

Due to the identical upper tetrachord that melodic minor and natural major scales have, the upper tetrachord of the natural minor scale is used to substitute the upper tetrachord of the melodic minor scale.

So, while playing the A melodic minor scale in descending form, the upper tetrachord of the A natural minor scale:

…is played instead of the upper tetrachord of the A melodic minor scale:

…and this produces the descending form of the A melodic minor scale…

A:

G:

F:

E:

D:

C:

B:

A:

…that is identical with the descending form of the A natural minor scale.

“In A Nutshell…”

The A melodic minor scale has a regular ascending form:

…that differs from its descending form (the A natural minor scale):

Final Thoughts

The reason why the ascending form of the melodic minor scale differs from its descending form is because the natural major and melodic minor scales are identical in their upper tetrachords.

The relationship between both scales makes it possible for the melodic minor scale to be derived from the major scale.

“Check It Out…”

Lowering the third tone of any given major scale by a half step produces the melodic minor scale. For example, the C major scale:

…can be used to form the C melodic minor scale by lowering the its third tone (which is E):

…by a half step (to Eb):

…to derive the C melodic minor scale:

…which has the same upper tetrachord:

…with the C major scale.

Thank you for your time and see you in another lesson.

All the best!

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Chuku Onyemachi

Head of Education at HearandPlay Music Group

Onyemachi "Onye" Chuku is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

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Tagged as: harmonic minor scale, melodic minor scale, natural minor scale, tetrachord, tetrachords, traditional scales