Our domestic ac was quite loud in the living area, hard to hear TV. I first used silver aluminum ducting tape to seal leaks, added 2 screws to hold up ceil cover, 6 total now. It has a slide vent that could be opened to add more air at this end of unit, I taped this off. Gaining on quieter. Removed vent deflectors, at the end of line holes runn kept going, I stuffed run and ducting taped to direct air out hole. Installed deflectors noise increased. Removed the end of run deflectors. Noise was less. Bought 3\4 spacers to put a screw thru, spaced deflectors down attached with 3 screws and spacers. Ac is quieter, air flow is better, 35 ' TT cools better.