how should I spend my money on this wall

This is an upstairs gameroom that is 17 x 22 x 8 feet. Three of the walls open to huge attic space and are sheetrock with only insulation on the attic side. I expect the insulation is not doing much to isolate the sound. The fourth wall opens to the outside and is typical sheetrock-insulation-siding. I will add layers of sheetrock to this wall. I am mostly wanting to keep the bass from getting outside the house to the neighbors. Adding sheetrock to the attic side would be difficult if not impossible to get a tight seal. The results would be STC36. Building a second wall with sheetrock on one side and insulation in the middle could result in STC57 provided I space it far enough apart. I want to preserve as much of the room as possible. How much of the STC57 will I give up if I only space it 5 inches (4 inch frame and 1 inch spacing) from the existing sheetrock? I will not reduce the ceiling height more than adding a second layer of sheetrock. The real question is if the ceiling is the weak link will building up the walls be worth the cost and space? Should I just add a second layer, or layers and possibly with RC or GG? While you are looking what do you think of the angled ceiling which runs the length of the room on both sides, is this going to cause sound problems?

Hi packrat - I think most members want to see a little more detail... but here goes my thoughts.

- you want to caulk and make the existing walls air tight.. you may be able to do this from the attic space side. - also, you may want to add the add'l wall on the attic side. That way you can get a good seal on the walls and not lose space.. however, I realize that may not be practical. - try using resilient channel or isolation clips between the new ceiling layer and the existing one. - if you can't get some ceiling seperation, then probably no point in building the double wall... just add sheetrock with GG and realize that your amount of sound blocking will be limited. - you can always add a more layers.. not an elegant solution bu eventually you may get what you want. - if you have any windows, deal with them first... probably your biggest sound leak. Make plugs or get a heavy second pane.

Creatch