social/reddit

That would be a seriously altered A7. It would be an A7b9#11. I can’t think of a context in which you would use those particular alterations.

To me that’s more of an Eb/A (that is, Ebmaj over a b5). That’s still weird by itself but try a progression like this:

Eb/Bb -> Eb/A -> Ab7 -> Eb

Notice the bass walkdown from the 5, to the b5, to the 4, then resolving to the I. To me that feels essentially like a simple reharmonization of:

Eb -> Eb7 -> Ab7 -> Eb

or in other words:

I -> I7 -> IV7 -> I

just in this case your I7 would have the alteration of a b5:

I -> I7b5 -> IV7 -> I