Affiliate Marketing Secrets

I just got a very nice new speaker system for my tv, with very good bass and everything
problem is, the only wall I can put it on is shared with my roommate’s bedroom. he has complained about the noise of it, which makes using it difficult
I was thinking what if I put thick fabric behind it, along the wall? I dont know much about acoustics, but would this solve the issue? would it reduce the sound quality?
It is in a niche, maybe only 4 ft tall and wide and a few feet deep. If I could just put something to cover the niche’s walls with, that would be best