I'm getting ready to start drywalling my theater and want to do some lower cost sound proofing to the ceiling. I was thinking about some fiberglass insulation between the joists and then double drywall. I'm not expecting it to be completely sound proof, but want to make it at least bearable upstairs. Should this do the trick? What is the best way to 'double' the drywall? Screw up the first layer, and then glue the second? Use screws for both layers? Should the seams be lined up or should I stagger them? Thanks.