Quiet Rock. National Gypsum’s sound-reducing drywall now comes in a thinner size for residential use. Half-inch SoundBreak XP is made by sandwiching a visco-elastic polymer layer between two sheets of high-density, paper-faced gypsum board; the increased mass and special damping properties of this construction make the drywall effective for high-rated STC wall partitions, says the maker. It costs just under $2 per square foot. National Gypsum, 704/365-7300. nationalgypsum.com