http://www.johnlsayers.com/phpBB2/index.php Here is a board that is all about studio design. They can def help out for something like this. Also the there are some books you can pick up on the subject. Essentially the most important part to "sound proofing" (btw sound treatment is an entirely different subject), is it needs to be as air tight as possible, and you'll need a gap between the walls to eliminate, or reduce, the transmission of vibrations through the walls.