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I have recently started adding augmented 6th chords to my part writing. As far as I can tell, I have not broken any harmonic rules in the displayed voicing, yet it does not sound right to me. Just wondering if I am missing something? Is there anything specific I need to know about how to voice these chords?

I know that typically German 6ths resolve to I64, but that is just to avoid consecutive 5ths. In this case, the B flat is below the E flat, so this problem should not occur.

The key here is G major.

P.S- bottom voice of the dominant chord should be F sharp and not G sharp. Rubbed it out to make it neater and then put the wrong note in!

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Thanks!

Ed

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    Looks like your V chord, D, has a G# instead of F#. I won’t answer because 4 part writing isn’t in my wheelhouse. Also to my jazz oriented ear these chords are substitute secondary dominants :) – John Belzaguy Mar 13 at 17:05
  • woops! thanks for pointing that out! – EdB123 Mar 14 at 19:26
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I can see/hear two issues:

  1. You have a cross relation between the soprano B natural in the first chord and the tenor Bb in the second. To hear this, revoice the first chord with the tenor doubling the soprano B. (Don't worry about the doubled third -- this is just to hear the voice-leading effect.)
  2. The tenor leaps into a dissonance against the soprano.

As a solution:

  • Since the third of the G major chord is not a leading tone, I believe it's permissible to double it.
  • Or you could re-voice the initial G major chord as (bottom to top) G-B-G-D, with the alto G leaping down to Eb.
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  • Also, is there a rule about entering a dissonance by contrary motion? Having the alto and soprano move in parallel sounds odd to me. I'll try to look that up when I get time, or something to check on your own in the meantime. – Aaron Mar 13 at 17:28
  • I wouldn't imagine so, or very many uses of diminished 7th chords would result in angry red markings from theory teachers. – Bennyboy1973 Mar 15 at 11:00
  • thanks Aaron- Yes, all other suggestions seem to suggest that the B in the first chord must move to B flat. Regarding the tenor leaping into the dissonance (2nd) 'against' the soprano, are you saying that the tenor and soprano here should be in contrary motion? They are in similar motion here. – EdB123 Mar 21 at 11:28
  • @EdB123 I'm not addressing either way similar vs. contrary motion between the tenor and soprano – Aaron Mar 21 at 13:23
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    @EdB123 Allowing for exceptions, but that's the general rule. – Aaron Mar 26 at 16:20
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Augmented sixth chords are almost always written with the lowered sixth scale degree in the bass. (The second most common usage has the raised fourth scale degree in the bass.)

As such, I'd recommend, at least for now, using that common voicing. Here, in the key of G, that would be with E♭ in the bass.

Coming from a tonic, the common voice-leading matrix would be something like:

B – B♭

G – G

D – C♯

G – E♭

(The lowest voice above is the bass, but the top three voices can be in any order.)

To resolve it back to V, then, we would use the following matrix:

B♭ – B♭ – A

G – G – F♯

C♯ – D – D

E♭ – D – D

Notice that we must go through the cadential six-four here to prevent the parallel perfect fifths. With the E♭ in the bass, it will always be below the B♭, thus we'll always have to watch for this error.

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  • Thanks for this brilliant answer. Just a question about the need to go to i64. Could the consecutive 5ths not be avoided by B flat soprano of aug 6th moving to D of dominant, and C sharp tenor of aug 6th moving instead to A of dominant? so it would move from P5 to P8? – EdB123 Mar 14 at 21:43
  • @EdB123 That's possible, but very rare. Think of that C# as a temporary leading tone; it has such a strong drive to move up to D that not resolving it there will sound a little off. – Richard Mar 14 at 23:18
  • If I recall correctly, in the case of VI(x6) - V, the parallel 5ths are tolerated as a special exception. I've always used the 64 - 53, or carried through with an Omnibus, but I'm pretty sure my theory teacher way back when made a point of highlighting this exception. – Bennyboy1973 Mar 15 at 10:51
  • @Bennyboy1973 Mozart so often ignored these parallel fifths that many now call them "Mozart fifths." I can certainly imagine that some teachers would follow in his footsteps and tolerate these as a special exception. – Richard Mar 15 at 10:53
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    @EdB123 Yes, both are valid options. You could even move to the higher octave for the E-flat and D and have the lower octave parenthesized for those that can sing that low. – Richard Mar 22 at 15:01

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