> have you ever heard of a material called "wall damp?" <
Again, what you need most is bass trapping, not wall damping. Now, if you have interiors walls that are not filled with fiberglass, that can be a problem. In that case you should either remove the sheet rock from one side and fill it with fiberglass, or use blow-in insulation. But this is in addition to bass traps, not instead of them. Understand that the resonances you need to damp are those that occur inside the air of the room between the opposing walls. Not so much the wall vibrations themselves.
--Ethan