I am currently building an MDF box to reduce the sound from a compressor. It uses 12mm MDF lined with carpet. What is concerning me is how much sound will escape from the cooling fan port (120mm circle) and the inlet holes for the fan circulation. I am wondering if I add some sort of convoluted tunnel to inlet and outlets, if that would make a difference?
This sort of thing
I am aware that speakers use ports to modify bass response, so would lining such a port with non reflective surface fix that? Or are there other and better ways to reduce sound emission from a cabinet via a cooling fan outlet?
Incidentally, I measured the compressor noise using a phone app at 90db, and then again when inside the cabinet, but with an open front, and it was actually louder at 92db. I'm picturing acoustic guitars that use their internal volume and port to amplify, and realising this might be more complex than I initially realised.