is an augmented second in the soprano avoided in 4 part harmony even when it occurs in a modulation?

Question

In this chord progression I wanted to modulate to the minor subdominant (Em to Am) but instead of just using a V7/iv I wanted to see if I could arrive to the V/iv in different ways and perhaps by introducing iiØ7 before the V. Here I chose a bII chord which acts as bVI in the original key and from here it descends by diminished 5th to a iiØ7 chord for a iiØ7-V-i in the new key. I realized after however, that I wrote an augmented second in the soprano. In a diatonic setting, I would be advised to avoid this progression and use a different soprano line but does this apply here as well?

NB, the V in the cadence is not a V7

Answer 1

I think the way to consider the problem is not so much about the line F♮ G♯ A and the A2 being "awkward", but rather the issue is about tendency tones and the tendency is for F♮ to descend to E and the G♯ to ascend to A.

The problem is you are not following the tendency of the lowered sixth degree in minor to descend to the fifth scale degree.

Not ♭^6 ♯^7 ^1 in one voice but ♭^6 ^5 and ♯^7 ^1 in two voices.

So, get the F♮ out of the soprano and into the alto, and have the soprano handle just the A G♯ A...

Answer 2

I don't mind the melodic aug 2, though it's not 'by the book' if you're trying to imitate Bach.

I'm more worried about the part-writing generally. You plonk the F♮ in very abruptly, in two voices. Then a rather clumsy F♮-B leap in the bass. And a lot of similar motion in the penultimate bar.

Answer 3

Given that you wish to follow the rule of avoiding an augmented second in the soprano in a diatonic setting, then yes, the rule applies here.

By the time the augmented second occurs, the progression has already modulated. The previous chord (bII of Emin; bVI of A minor) is the pivot chord.¹ Thus, having modulated to A minor, the augmented second is within a diatonic context.

¹ _{The Vmin7b5 (that follows the bII) has no functional meaning, and, even leaving that aside, then, as @MichaelCurtis points out, if you're going to follow the "rules", the F must resolve downward to E.}

Answer 4

This is why the melodic minor scale exists. You could avoid the augmented 2nd by re-sharpening the 2nd F-natural. That chord would become ii7 in A minor. To avoid that nasty tritone in the bass, you could move the bass from B to D, making it IV in A minor.

And I think Michael Curtis and Laurence make good points as well. This is just another option.