Covering soundproofing question?
My workmates and I work in booths with the walls covered with foam soundproofing.
We have an argument.
Some say that it's OK to cover the walls with cloths, posters, etc.
I say that if you do that, you are making the soundproofing useless, as it is the shape of the foam that the audio waves need to hit. Hitting a sheet will reduce the ability to absorb the sound.
Which is correct?
Sources would be appreciated.