Wall density vs room modes-Acoustics Forum-Acoustic Fields Forum

Hi. I have a dedicated music listening room in the attic. It is difficult to get good coverage of fullrange acoustic treatment, because almost the entire ceiling is slanted. Currently the slanted ceiling consists of multiple layers, and a total thickness of about 4cm. I currently have big issues originating from around 30-40hz.

The current ceiling have to be changed for other reasons, so i am free to choose what the new ceiling will consist of. If i use much thinner material for the ceiling, like one layer of 10mm mdf, will those low frequencies simply pass through instead of bounce around inside the room?

Thanks.