Our air purifiers make about the same amount of noise as the average computer fan, much less than a micro-wave or air conditioner. Our air purifiers use a very quiet 5 speed fan, similar to a computer fan, this pulls enough air through the air purification chamber at a rate that creates optimum levels of purifying plasma. If sound level is an issue, select a slightly more powerful air purifier and run it at a lower speed. On low speed our air purifiers are so quiet you would have to lean down and stick your ear within inches to even be able to hear it running, and even then, most of the sound would be the slight whoosh of air passing through the air purifier.