re sound deadening materials for a control room.
up further in the tips.
(addendum).
Russ Demussel sent me the following pm....
which i'll quote in its entirety as an option for folks to consider.

"In reading your tips about cheapo sound deadening materials I have a suggestion you might add to it. You can get foam carpet pad. It's cheap as it gets. It's usually around 4 to 6 feet wide and you can glue/staple it to the walls and cealing. That's what I've got in my sound booth. Blue carpet pad. And it is fire resistant. Very hard to get it to burn. It will melt and puts out a horrible stink when burned. but doesn't seem to flame up. Just a thought. "