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:
When writing in four voices, what’s the best note of an Italian augmented sixth chord to double?
- A) The Root
- B) The Third
- C) The Sixth
Hint: choose the option that avoids parallel octaves.
Reply to post your answer, and check back on Friday, September 10th to see if you’re right!
ANSWER for 9/7/21
B) The Third. The Italian sixth is the only augmented sixth chord with only three notes, so in a four-voice texture one of them has to be doubled. If you double either the root or the sixth, you get parallel octaves. The only note in the chord that can resolve either up or down is the third, so this is the best note to double. On the staff below, we have an Ab Italian sixth resolving to the V chord in the key of C minor. The third of the Italian sixth, C, can either resolve up to D or down to B. So the alto and tenor double this third, avoiding the parallel octaves you’d get by doubling either the root or the 6th.
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B
6th
Hi Paul! Thanks for braving this week’s challenge, but you wouldn’t actually want to double the 6th. The augmented 6th can only resolve in one direction, up a half-step to the root of the V chord. And with two voices doing that, you’d get a nasty case of parallel octaves. In the Italian 6th, there’s only one note that can resolve in two different directions, and that’s the one you want to double 🙂