Show off your theory chops with my weekly challenge! You’ll find a new question here every Monday. Please comment to post your reply.
This Week’s Challenge:
Within the context of common practice music, the harmonic minor scale solves one problem but creates another. This week’s challenge is in three parts:
a) What problem does the harmonic minor scale solve?
b) What problem does it create?
c) How is this problem solved?
Post your reply and come back Friday, April 22nd for the answer!
ANSWER for 4/18/22
a) Harmonic minor exists for––you guessed it––harmonic purposes. It solves the problem of a natural minor scale, from which you can only build a minor V chord. This makes the authentic cadence, which requires a major V chord, impossible. By raising the seventh note of the natural minor scale, this gives the scale a leading tone, which changes the V chord to a major triad, thus making a true V–I authentic cadence possible.
b) By raising that 7th note to create the harmonic minor scale, we leave a large “gap” between the 6th and 7th notes, an augmented 2nd. To 18th-Century composers and theorists, this interval was just a bit too awkward, too difficult to sing, and (as befitting a rather ethnocentric West-European mentality) too “exotic” for a diatonic scale.
c) To “correct” the problem and smooth out the scale, we add a third type of minor scale: melodic minor. Raise the 6th note a half-step, and we iron out that large augmented 2nd and make the scale easier to sing, with just half-steps and whole-steps to contend with.
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An augmented second (F-natural to G-sharp) is difficult to sing; solution is to raise the F to F-sharp (melodic minor scale) and make that interval just a whole step.
The raised 7 creates a leading tone to the tonic which is a major 3rd of the V chord thus establishing diatonic functionality of the V to i.
Problem is the augmented 2nd created between 6 and 7 difficult to sing
Solution is mode mixture; using melodic minor.