I did a little research and found a site that tells you how to build acoustic panels:
http://acousticsfreq.com/how-to-build-your-own-acoustic-panels/
Apparently, fiberglass board insulation at least two inches thick is needed. The sample construction uses 2″ Roxul RHT 80 at $0.78 per square foot.
As far as decorative fabric, anything that is acoustically transparent, where the sound can reach the fiberglass. The page suggests putting the fabric up to your mouth and blowing through it to see if air freely flows through it — so I guess the lighter the better.
http://acousticsfreq.com/how-to-build-your-own-acoustic-panels/
Apparently, fiberglass board insulation at least two inches thick is needed. The sample construction uses 2″ Roxul RHT 80 at $0.78 per square foot.
As far as decorative fabric, anything that is acoustically transparent, where the sound can reach the fiberglass. The page suggests putting the fabric up to your mouth and blowing through it to see if air freely flows through it — so I guess the lighter the better.