Speaking of noise, the crickets are mighty loud this evening.
What it boils down to is this: you'll probably just have to try something. That something would likely include cutting and replacing some sheetrock. You could cut holes in the ceiling and pack insulation around the pipes. If it REALLY bothers you, access all the wastelines by cutting into the ceiling, demo the plastic pipe, and install no-hub iron. Iron is dead quiet. This would disrupt your life considerably unless it were part of a larger remodeling project, which would disrupt your life considerably.
Did a new house where, unfortunately, the upstairs bath toilet ended up dead center of where the dining room table would go. Remember Archie Bunker? Anyway, we did that bathroom in no-hub iron and that solved the problem.
