This one will be hard to believe. We have a 1735 farm house. Two years ago we replaced most of the bathrooms, but the main waste stack stayed in place. When the house is quiet in the evening, we all clearly hear the wind going across the main waste stack on the roof. It's sounds like a young kid blowing across a soda pop bottle. Or a sick flute. It's loud enough to hear from any place on the second floor. Any hints on how to change this?