Yo Chet,
You might try using half inch thick fiberglass insulation with foil on one side. Spread a thick layer roofing mastic on the fiberglass side and cover it with a burlap or cotton duck cloth. These come in 4 x 8 sheets and the cloth will come in 60" wide bolts. Buy about 3 yards for each 4x8 and finish nail or double stick tape them foil side to the wall. It should reduce the bass at least 6db (75%) in the neighbors room. If you have any money left glue the 3/8" cork on to the foil side of the fiberglass. If you can't afford to cover the whole sheet with cork, use strips every foot or so to keep the fiberglass panel off the wall. The fiberglass panels should run about $12 each from an insultion distributor the cloth about $3-$5 yd. at Wal Mart and the mastic about $20 for a 5 gallon bucket at Home Depot. You can cut the fiberglass panels with a razor knife to fit around objects on the wall. The only trouble will be that your neighbors above and below will probably complain when you start cranking it up.
You might try using half inch thick fiberglass insulation with foil on one side. Spread a thick layer roofing mastic on the fiberglass side and cover it with a burlap or cotton duck cloth. These come in 4 x 8 sheets and the cloth will come in 60" wide bolts. Buy about 3 yards for each 4x8 and finish nail or double stick tape them foil side to the wall. It should reduce the bass at least 6db (75%) in the neighbors room. If you have any money left glue the 3/8" cork on to the foil side of the fiberglass. If you can't afford to cover the whole sheet with cork, use strips every foot or so to keep the fiberglass panel off the wall. The fiberglass panels should run about $12 each from an insultion distributor the cloth about $3-$5 yd. at Wal Mart and the mastic about $20 for a 5 gallon bucket at Home Depot. You can cut the fiberglass panels with a razor knife to fit around objects on the wall. The only trouble will be that your neighbors above and below will probably complain when you start cranking it up.