We recently purchased a home. It is about 20 yrs old with many renovations done to it. (I should mention we live in a region which currently gets close to freezing at nice and warm in the afternoon). Recently we are hearing a noise in the upstairs bathroom. When we run the bathroom sink we are hearing what sounds like a loud dripping sound. As a test I filled the sink with hot water alone, then cold water alone. The sound occurs when I release the water into the drain. The strange thing is the sound can be heard in the attic, and basement. Now of course there are no water pipes in the attic, and I can see the water and drains pipes in the basement and I do not see any water. My gut feeling is this sound is "the sound of the house", but I want to see what others think.