To really sound proof or severely dampen sound you must use the heavy foam made for this purpose. For mild absorption of sound cork will do. A quilt may muffle mildly sound but it is not going to, by any means, soundproof a room. As an example cover your ears with a quilt and listen to the mild changes that is about all it is capable of doing. I use quilts to absorb trace sounds but that is the max you will receive.