As a long-since lapsed engineer I'll take a stab at the noise matter and then those who actually work in the field can correct me.
Seems to me that the main variables affecting arena noise are: (1) size of crowd; we get a lot of fans in the AH at capacity; (2) volume of air between fans and roof; sound propagates through air; (3) reflective capacity of the roof material v. absorptive capacity regarding sound waves; (4) angle(s) at which sound reflects from roof back into the arena.
Dense concrete, as I recall, is a very effective sound reflector. This is what the AH roof comprises (I assume it's dense and not porous concrete). So: effective sound reflector. However, because of the domed geometry of the roof, the reflection of sound back into the arena occurs at various angles. (For example, a flat surface would reflect most sound in a largely downward. In the AH it's reflecting off the other side of the dome, too.) In addition, the dome is not smooth; it's serrated (not really the right word but that's what I'll call the concrete folds in the roof) and so the reflection of sound waves is even more complex. In addition, the apex of the dome is really high. There's also a lot of air in there to attenuate sound waves as they're reflected, compared with an arena having a steep bowl with a flat roof directly above it.
A flat metal roof closer to the crowd seems intuitively to reflect sound back down at the crowd and floor more effectively than any concrete dome, let alone a serrated one like ours with a very high apex.
So, having never been in Mackey for a game here's my hypothesis: it's got a steeper bowl than the AH as I recall, a lower volume of air in the arena, and a low, flat, roof. It's like a tight metal drum. And while it seats fewer fans (14.1k v. 15.5k in the AH/SFC post-renovation) I'd guess that this doesn't reduce its noise advantage significantly. Therefore, I'm guessing it's a louder arena than ours when it gets rocking.
That's my amateur civil engineering/physics take from someone who ended his mechanical engineering studies 33 years ago and never put them to professional use. I will now leave it to a graduate of the top civil engineering program in the world (UIUC) to drive a large truck through the holes in this analysis and complete the public self-embarrassment that I've initiated.