We've been in an inside stateroom on the Wonder, midship deck 6 a couple of times. We were right over the Oceaneers Club (I think). Sometimes you could hear it a little during the day, but they tone the noise down a lot at night and, of course, they're not open too late, so sleeping was never an issue.
If you're one to stay in your stateroom a lot during the day, perhaps you could have an issue, but that's exactly when we tended to not be in the stateroom.