Half-diminished pentatonic scale?

Question

The traditional minor pentatonic scale heard in jazz contains these scale tones: 1 ♭3 4 5 ♭7. For example, in Cmin, this would be C E♭ F G B♭.

By contrast, the major pentatonic scale has these scale tones: 1 2 3 5 6. For example, in Cmaj, this would be C D E G A.

There is another minor pentatonic scale I've heard used in jazz solos. It has the same scale tones as the major pentatonic, but it uses the flat third. Here's that alternate minor pentatonic scale: 1 2 ♭3 5 6. For example, in Cmin, this would be: C D E♭ G A.

This alternate minor pentatonic scale sounds great over Cmin6 and Aø7, and those are the two contexts in which I've primarily heard it used. I would also expect it to sound good over F7 and E♭♯11.

My question is: does this scale have any theoretical basis? If so, what is its name, and does it have any function outside of jazz / outside of the applications I've described above? If it has no other function outside of jazz, then when analyzed from a theoretical standpoint, is it nothing more than a minor pentatonic scale (1 ♭3 4 5 ♭7) with a flat fifth (1 ♭3 4 ♭5 ♭7)? If constructed this way (from a minor scale but with a flat fifth), then the second mode would give the minor pentatonic scale described above (1 2 ♭3 5 6).

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Note: with a little researching, I found the scale referred to as the "half-diminished pentatonic" (see p. 1 of this doc and p. 1 of this doc), but I've also seen it referred to as "Dorian Pentatonic, Kumoi Japan" (see p. 1 of this doc).

Answer 1

This scale is based upon the Dorian mode and the first inversion half-diminished chord.

The Dorian mode was a popular mode during the Renaissance (1400-1600) period of music. Modes became less favored during the Baroque (1600-1750) and Classical period (c. 1750-1825) due to the rise of major and minor tonalities. Romantic composers loosened the forms and tonalities established in the former two eras, which led to more color as in this particular scale or chord. Composers even explored older forms as in the case of composer Johannes Brahms, who was well studied in the Renaissance modes (Mason, 196). For example, he would use the Dorian mode and the first inversion half-diminished chord in the first movement of his Vier Ernste Gesange (1896) by way of chromatic voice leading.

This chromatic voice leading would also be another reason why they used this particular scale (In actuality, this is not so much a scale as it is an arpeggiation of a half-diminished chord in first inversion.). Putting this chord in inversion would allow for smoother voice leading in composition. It would also mean less tendency for error as in the traditional study of counterpoint by avoiding diminished to perfect intervals of fourths or fifths. Instead, it would be more likely for the diminished interval to resolve inward to a third, which was more pleasing during the time. This practice would also soften the harshness of a half-diminished chord in two ways:

1. It took the diminished interval from having its root in the bass, which would sound more prominently
2. It allowed for the diminished fifth to be less stark because the 7th of the half-diminished chord would rest in between the root and dim. 5th

The first inversion half-diminished chord or minor add 6, as in Cm6, may also have been used in order to create ease of arpeggiation.

This is how I perceive this chord coming about. There is so much more than what I cite put into this, and so much more one could add. But we know this scale is a half-diminished chord in first inversion and it emphasizes the Dorian mode.

• To clarify, the Dorian mode was used in the Renaissance period without emphasis on exoticism due to their familiarity with church modes before the rise of major and minor modes somewhere between Renaissance and Baroque period. Because they would be playing in the Dorian mode, they would likely encounter multiple melodies involving 1-2-♭3-5-♮6 scale degrees. Where this comes back in the Romantic period is with composers who were well versed not only with contemporary techniques but earlier methods such as those in the Renaissance period. Because the Dorian mode may be emphasized, this half-diminished pentatonic scale may be emphasized as a natural result of the Dorian mode itself. The other direct relationship with this particular subject may be to realize it as a half-diminished first inversion chord (or more easily viiø6/5 or iiø6/5 depending on whether major or minor mode), which is exactly the 1-2-♭3-5-♮6 scale degrees of this subject. This chord in particular began to be especially emphasized with the rise of chromaticism that Beethoven brought as a transitional figure between the Classical and Romantic period, which subsequent composers began to treat more loosely as time went on. Thus we have Brahms in the latter half of the 1800's who can be seen using this very subject. Other composers you may see use this chord/scale/mode, possibly would be Chopin, Liszt, Schumann, Debussy (escpecially loved modes and exotic scales), etc. I would shy away from saying these composers used them so often that one would immediately find this melodic sequence, because their theoretical vocabulary in composition was so vast that I believe they would have been able to use them more sparingly among other techniques. However, the half-diminished chord in first inversion was very familiar in this period for the benefits to counterpoint listed above.
• Another interesting item is that the diminished scales of whole/half and half/whole (or octatonic scales) can be seen used with Alexander Scriabin's Vers La Flamme, and Debussy's Nuages.

Reference:

Mason, Daniel G. “Brahms,” in Grieg to Brahms. New York: The MacMillan Press, 1940. 196.

Answer 2

What you've found is known as the Melodic Minor Pentatonic Scale (as already hinted at in Kolob Canyon's comment). It is derived from the melodic minor scale by removing the 4th and the 7th scale degrees, in the same way as the major pentatonic scale is derived from the major scale. Equivalently, it can be obtained from the major pentatonic scale by lowering the third, or from the relative minor pentatonic scale by lowering the 5th (both of which you've already mentioned).

Clearly it can be used wherever the melodic minor scale and its modes can be used. The C melodic minor pentatonic scale

C D Eb G A

could for example be used over the following chords:

Cm6
Eb maj7(#11)
F13
Am7 (b5)
B7 (#5,b9,#9)

One more typical application would be in the blues, where you could play the major pentatonic scale over the I7 chord, and, by lowering the 3rd, you could elegantly switch to the melodic minor pentatonic scale over the IV7 chord. Note that it's the melodic minor pentatonic scale with the root of the I chord (not the IV chord). In a blues in C that would mean C major pentatonic over C7, and C melodic minor pentatonic over F7. In this way you can adapt motifs that work over I7 and play them over IV7 by just changing one note.

Answer 3

While you are pondering this, you might enjoy checking out Vincent Persichetti's naming of various other possible pentatonic scales and their inversion forms in his book "Twentieth Century Harmony". He also points to usages in world music, both classical and folk.

1 2 3 5 6

1 2 3b 5 6

1 2 3b 5 6b

1 2b 3b 5 6b

(I can't recall if he also included 1 2b 3b 5b 6b in this discussion. I should get a copy of his book for my library.)

And any time I hear about "theoretical justification" I find myself thinking about the hundreds of ragas, many of which are pentatonic and do not fit into the more glib Western constructs.

I think it might make more sense to look at things from a kind of "Pitch Set" perspective. Any restricted set of five notes (or four notes, or six note, or whatever), if used in a disciplined, artistically controlled manner will have expressive qualities that can be exploited in a musical fashion.

Answer 4

While not a satisfying as a scale with a specific name, couldn't you just say it is the half-diminished chord with a passing tone between the 3rd and 5th of the chord? 4 of 5 of the tones are chord tones. I'm assuming the notes are all played conjunctly.

I don't mean to be glib. By comparison when I hear the harmonic minor scale played over V7 I often think it could be described as the chord arpeggiated and filled in with passing tones.

Answer 5

No, I wouldn't relate them.

To me, one of the main points of a pentatonic scale is that because there are no half-step intervals, you can run up and down and all around the scale in any order you want, and never paint yourself into a musical corner where the next note feels like it needs to resolve.