Okay, you may not find this helpful but I would put carpeting up wherever you think the sound is penetrating whether it be on the floor or the walls. The carpeting will help diffuse the noise. Then at least you can prove that you have done everything that you could to correct the situation. And I have actually seen this done when parents didn't want to hear the stereo from their son's room. On the walls it makes a rather interesting conversation piece. I know it sounds kooky but it worked for them.