Outside walls 1&2 are sheetrock & brick. Inside wall #1 will be sheetrock insulation and sheetrock opening into a theater snack room whose wall (opposite side from theater side wall) will be sheetrock, insulation, sheetrock and the main house. Wall 4 will be sheetrock, insulation, sheetrock and the main house. Why do I need more insulation soundproofing than this? Will another sheet of sheetrock help (current is 1/2 inch)? on the inside walls? Is there something better? Thanks for the guidance.