A:Answer I have 3 of these running 24/7 in my home. One in the living room and one in each bedroom. I just recently purchased the third one for the 2nd bedroom after having the other 2 for almost 4 years. I chose to purchase these rather than try different brands or models because they do a fabulous job of cleaning the air and the sound coming from them is quiet and soothing, really. There are several speeds for filtering, and the higher the speed the louder the sound, but I don't find the highest speed to be at all loud and annoying. The majority of the time all 3 filters are running on low; I will run them at higher filtration during the day when pollen in the air is at a high, or in the winter when mold spore could be a problem. I hope that helps...
