Dear Sylvan,JWA suggested to me that you may be able to help.The noise from the upstairs toilet can be heard in our downstairs livingroom.The toilet which is above a closet in the living has had styrofoam insulation put around the down pipe and covering the inside of the door it softened the noise but not enoughny suggestions.Thanks Diane
I hope your plumbing drainage system above ground is not plastic (GARBAGE) you see Plastic is known as the noisy pipe and the carcinogenic piping of choice in fires.
If you can contact a licensed plumber have them replace this drainage with Quiet long lasting safe Cast Iron (even no hub cast Iron is better than plastic) A lot of stumble bums knowing how bad plastic is in drainage systems try to cover up this fact with Styrofoam and some even resort to fiberglass insulation all around it as a sound deadening scheme.
Unfortunately the home builders rely on cheap materials and even cheaper non skilled techs to install plumbing these days and the result is the home owners hearing their plumbing WHICH was unheard of years ago. The only suggestion I can give is to try to find out the exact material you do have for your drain and waste piping and E mail me privately and we can discuss options including suing the installer if they used Band iron instead of clevis hangers or other CODE APPROVED supports at the recommended distances. IM so sorry to have had to lay this on you good luck.