This product known as ‘sound board’ is distributed at home improvement stores, drywall distributors, and other stores online. Performance from sound board and sound board type products have no real place in wall and ceiling construction. Any panels hung on your walls and ceilings should have as much mass as possible. Sound board has very little mass so including a layer of sound board will not increase performance any more than a single layer of drywall. Some increase in performance is had by the very light decoupling it can provide between drywall and framing, but those gains are quickly lost due to the product’s severe lack of mass.
With that said, including sound board in your floors will have a decent increase in performance. It will not be as significant as QuietGround Rubber Underlayment or Green Glue Compound in your floors, but it will perform noticeably better than just another layer of plywood.
Our Advice: Sound board, and similar sound board type products, are okay for floors, but a waste of time and money in your walls and ceilings. If you want layers then stick with something that is cheap with higher mass like drywall.
