Rip out the drywall and insulate in there. Addressing the finished room,after the fact will suck up the sound--necessitating more volume to overcome the treatment. Oh, and don't expect much control in keeping bass from going thrugh the wall/s.
Sound proofing any suggestions
When I listen to my music I want to be sure that know one else is being disturbed, therefore I am in the process of sound proofing my listening room.Any suggestions as to what will keep the sound from going through the wall which is plaster with two layers of sheet rock that I added hoping it would make a difference. Also since I am into health I am avoiding anything that outgasses therefore no foam or smelly materials. One of my first options are fibergalss the one that is less toxic. thanks