Timlub- are you talking about corner traps? For the walls I have thin wood (pegboard like) 2'x4' boards and 2'x4'x2" high density fiberglass panels to glue on and wrap in fabric. I'm placing 8 panels on one wall and 4 panels on another (planning to buy another 6 - 18 total).
When I bought panels salesman showed me the room with walls made of similar material and effect was incredible. I could hear his voice so pure and coming directly from his mouth. I know that acoustically dead room is bad for music but I'm very, very far from that. I have a lot of reverberation in 15'x25' room that has cathedral ceiling starting at 12' (a lot of walls). Thinner materials like fabrics or blankets don't do any good. If you place such material if front of you and can still hear thru it the it is no good (won't stop wall reflection)
When I bought panels salesman showed me the room with walls made of similar material and effect was incredible. I could hear his voice so pure and coming directly from his mouth. I know that acoustically dead room is bad for music but I'm very, very far from that. I have a lot of reverberation in 15'x25' room that has cathedral ceiling starting at 12' (a lot of walls). Thinner materials like fabrics or blankets don't do any good. If you place such material if front of you and can still hear thru it the it is no good (won't stop wall reflection)

