Not at all noisy. I found that rooms away from the elevators had more noise. People walking down the halls talking.
Another thing that was important for us was that there was a room across the hall from us, or the elevator shaft. There are some rooms on Emerald deck that have a plain wall across the hall from them. I found that there was a hissing noise from what was ever behind the wall. At times I could hear it in the cabin. I have been on Regal 15 times and all time (after the hissing rooms) stayed by either the mid ship or forward elevators. 319 is also a nice cabin.
Cabin 436 is over a bar. There might be noise from that.