What effect does density have on sound absorption coefficien

[hugo_inside]

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 ??

[Ethan Winer]

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

[hugo_inside]

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?

[Ethan Winer]

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