How to construct a super sound insulated music rehearsal space?
What you want is an air space to stop sound transferring through to the outside wall. Besides using insulation behind the first dry wall layer, add firring strips (I say about 1/4″ thick) perpendicular to the studs over the first layer of dry wall and add a second layer of dry wall over the firring strips. Then cover the walls with paper egg cartons. Just open them up and staple them on. This will stop the sound waves from bouncing off the walls.
