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 approaching a cadence, you’ll very often see a I chord in second inversion (I 6/4). It’s called cadential 6/4, and you can see it below in this excerpt from Scott Joplin’s Maple Leaf Rag. What harmony does this chord really imply, and why does it function this way?
Post your reply and come back Friday, March 11th for the answer!
ANSWER for 3/7/22
A triad sounds most unstable in second inversion. This is because the bottom interval is a perfect fourth, which is technically treated as a dissonance because of its tendency to resolve down to a major 3rd. So near a cadence, a I 6/4 chord really sounds like a V chord with a couple of suspensions above the bass. The 4th, in particular, wants to resolve down to the 3rd of the V chord. So, near a cadence, a I 6/4 chord is really a delayed dominant, or, put differently, an expansion of the dominant harmony. You can also think of I 6/4 as a dominant that hasn’t put the other shoe in yet!
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There’s probably a fancier answer, but to my Ears I always hear the I 6/4 as a V7 sus, so essentially just V-I
*V sus*..
no 7
I always hear a cadential 6/4 chord as a V chord with double suspensions (6-5 & 4-3). It functions as a V with accented non-chord tones. The resolution of the non-chord tones on an unstressed beat strengthens the ultimate arrival of Tonic.
It is one of the predominant options (ii, IV, Aug6, V6/4, etc). A cadential 6/4 is the antepenultimate, followed by the penultimate V, ending with the ultimate I.
What everyone says is true. It’s also the fact that it’s a second inversion chord are not as stable as a root position or first inversion chord. The fifth of the chord (dominant) in the bass Creates a Pull towards the tannic.
The idea of a double suspension on a V chord is right. Ab to G (4-3 suspension) plus a C to Bb (6-5 suspension) at the same time.
But the Bb is missing in the next chord in this example. Instead, there is a Db, which appears to lead from the previous C, denying the resolution of the suspended C. So perhaps in more modern times the cadential 6/4 has taken on a more independent role than in traditional classical times?