wide seams: mud vs acoustic caulk

Hey all. I've got some relatively large seams (5/8" in places max) between a couple of sheets of drywall (it's my 3rd layer and the "out of square-ness" of the room got amplified with every layer it seems). Anyway, I'm wondering if it'd be better to fill these with acoustic caulk (osi-175) or just mud/tape them. I guess the mud/tape idea would create a much better looking wall in the end but I'm wondering if it'd be better for isolation to fill them with acoustic caulk. My isolation is already pretty damn good but I'm like an isolation addict now. There can always be more I guess. Thoughts? Thanks.

Well, which ever why you choose know this. With a wide crack between panel you should skim mud into the crack. Let it dry. then bed the mud and tape it. If you do not fill that void the paper will flex and be a pain in the behind to make flat. Your choice, it just depends on what kind of interior finish you are going more. But if this is not the last layer, caulk of the acoustic kind works wonders.