A:Answer Compared to other HEPA filters, especially some of the older TrueHEPA units, the noise levels are very much reduced, as it has better airflow, so the fans don't have to work as hard. It has four fan speeds, though you'll likely only notice it's running on the three highest. The slowest fan speed is Sleep mode, and you'd have to get very close to the unit and pay attention to notice it's running. The next speed, General, moves more air and the fan noise is more noticeable, but only if you're listening for it. The third mode, Allergen, is a bit noisier, but also moves a lot of air. The third mode would be perfect for those who desire white noise while sleeping - noticeable, but not too distracting. The fourth mode (Max) is quite noticeable, but the smaller diameter fans contribute to the fan noise, giving it a higher pitch "buzz" when it runs on high speed.
