ok but then which one to trust?
Are the 60kg/m3 9cm thick (would double them up to 18cm thick) rockwool plates with air flow resistance of somewhere between 16k and 50k I'm about to buy, good at absorbing the bass in my room or not?
PAC says no, measurements say yes.
And I have no idea which one to belief and I don't have the money to try out and fail.
Surely many here must know as it has been done so many times in practice before right?