Looking to acoustic treat my room. I want to get safe, non toxic acoustic treatment that still has good sound absorption. Looking for the material wise, since different pieces would be used for different frequencies. Want it safe to breath (even if not covered by fabric), also safe in case my dog accidently chews and swallows some. Also safe to handle.

I am using a 12 by 24 foot room as a home studio and this room echos like crazy. Every time my guitar players and I jam or record the echo makes it sound like a bunch of jumbled notes. Some advice on what kind of studio foams or other cheap alternatives would be great, thanks.