Get a load of this site, www.quietsolution.com They sell products online for high STC construction. They actually have a 4x8 sheet of drywall with an STC of 38!!!! Of course it is 1 1/2 inches thick, weighs 200lbs. and costs $190 + freight! I did print out their "Soundproofing Home Theaters & Media Rooms" booklet, it looks to have some interesting info.