I bought this because Wirecutter said it was a relatively quiet model. Unfortunately, the filter vibrates against the front panel, causing a loud and annoying buzzing sound. LG sent a technician out to look at it and he said that the filters are poorly designed and too thin, so that's why this happens. Nothing they can do to fix it. He recommended putting tape all over the machine to try to stop the vibrating, which is definitely something you want to do to a brand new unit in your living room. But I did try, and it didn't work. 

LG refuses to replace the model, saying that it is functioning correctly. Which tells me that LG thinks a buzzing sound that is significantly louder than the dBa levels promised is just part of the design. Now I run it without the filter in because the buzzing drives me nuts. I'll be replacing it next year. Buy at your own risk.