often have to hold my hand over the top to feel the air movement to know that it is running. But, even though this is in our family room, if the bacon gets burned the slightest in the kitchen, you can hear this ramp up the fan until the air is clear, so we know the air quality sensor does work. We purchased this model because when I researched the availability of filters for some of the other models, they were all listed as out of stock, backorders, or just unavailable. This model seems pretty standard so you can get filters from third parties if you like. It really is quiet!