ISO: Felt for sound proofing/deadening

Hi Cubers! I am making a small choir room. I want the sound in the room to be relatively dead. I was thinking of hanging 1/2'' felt on the walls, and have gotten a quote from Southerland Felt Company. But I wanted to check here in case someone has good advice on how to do this cheaper, or in case someone had a lot (360 sq ft) of felt lying around, etc. Please help! Thanks!!!