The Cube has a single-speed fan that you can hear, and which produces “white noise.” It’s not terribly loud, but you can certainly hear it in a quiet environment. Based on the official specifications, the Cube produces noise in the range of 51-56 dBA at one feet distance with 40 dBA ambient noise. For comparison, a quiet dishwasher registers at around 50 decibels and a washing machine at around 70 decibels. My wife and I sleep with a white noise machine on at night, so we weren’t disturbed by the fan noise. But if you’re used to sleeping in a totally quiet environment, you might find the fan noise bothersome.