Quote Originally Posted by deeaa View Post
That's pretty much what those white panels are, similar stuff but especially designed for audio use. A few dozen of them on the walls, ceiling, and corner in a slant & filled with more fiberglass.
The white panels are not abosorbing mid or low frequencies. In order to do that, you need at least a 2 inch air gap between the panel and the wall or ceiling.
And the panels need to be much thicker and more dense. Generally, either owens corning insulation, or Rockwool. 4 to 6 inches thick at least.