What effect does density have on sound absorption coefficien

if the material is mounted directly on solid wall, what effect does density have on sound absorption coefficient?? What will be better 80 mm low density glassfiber or semi-rigid 40 mm ??

Hugo, > if the material is mounted directly on solid wall, what effect does density have on sound absorption coefficient?? < It depends on the thickness. I recently performed an extensive series of tests on density, and found that when the panels are made thicker you can get away with less density. Here's a link to the full report: www.ethanwiner.com/density/density.html --Ethan

Hi Ethan, thanks for anwering. very interesting experiment. Perhaps your article gives me a good idea. I have a problem: I want to build my own absorber panels, but the cover FABRIC is a problems because of flames. I'm building a some rehearsal rooms, and people usually SMOKES when they rehears. That's the problem. But reading your article I have the idea of use Fiberglass with kraft paper. What do you think of this way?

Hugo, > the cover FABRIC is a problems because of flames < Not really. In a fire, thin fabric burns up immediately and is no longer a problem. What matters most with fire ratings is the mass of the flammable material. --Ethan