Depends on when you plan on sleeping.. the main shows are done by midnight at the latest. We had a cabin directly above the theater on our Valor cruise. If you were in the cabin during the production shows and were quiet you could hear the music but it did not keep us up. Of course we were normally still out having fun when the shows were running.
You shouldn't have any issues.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007