We were on Vision on deck 4 in 4572 (starboard side, just inside the centrum).
Even though there were a lot of activities in the centrum we never heard any noise inside our cabin.
Occasionally we heard a little noise from the promenade above us, but that was only when the window washing crew was up there or they were lowering tenders. Even then the noise was never bothersome.
You will love the Vision class and I have heard that the Grandeur consistently ranks first for customer satisfaction in the RCL fleet.