Where is the AOSP Volume Up / Down UI sound?

I have a personal hatred for the default Vol Up / Down sound in AOSP, and even though a few have asked before, no one seems to know where this file lives in AOSP. I want to change it so, so badly, and it doesn't seem to be in /system/media/audio/ui or any of the other /system/media/audio/ folders.

Anyone know where this file is?