Soundproofing is an advanced science on its own. There is much more to it than just applying dense muffing materials. For one thing, though you might want a room soundproofed, so that no sound enters or escapes, you don’t want to distort or deaden the sounds in the room. In private rooms, there are generally two reasons for soundproofing. The first is to enhance the sound in a room, for example in a home theatre or a music room. This implies insulating against reverberation and echo by using...