Well, I only have the 6 cruises and I can't remember hearing any sounds for the next cabins. You hear hallway noise, and on our Conquest cruise, we think we were one deck below Camp Carnival and you could hear thumping during the day hours (from the kids jumping around) But nothing at night.
Maybe if you were in the bathroom, you could hear the sounds coming through, but you would have to be really wanting to hear them. The toilet flushing makes a lot of sound and you can hear that.
I wouldn't worry about it.
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, Celebrity Silhouette 2013