This is not a home studio but a classroom studio that I need some acoustic help with. I have carpet on 3/4 of the walls and carper on the floor. The back wall which is a green wall is a hard surface and the big observation window we have from our control room is also hard. I have put up over 36 3" foam acoustic tiles on the side walls to help and it has but not enough. The ceiling is suspended but it has been painted black which may have taken away much of the acoustic properties. I do believe much of the resonance is coming from the ceiling. Is there something anyone would recommend to help that could be placed on the ceiling? Burlap? Foam? Does anyone know or can you steer me in the right direction? Thanks.