The Smart Topper is nearly silent when cooling is at a low level. At 50% level of cooling it’s equivalent to a forced air household heating noise. At
full cooling, it sounds similar to a stand-alone fan running in the
room.
The level of cooling selected will determine how loud the fans
will run. If you're sensitive to sound, there is a quiet mode setting in the app that constrains the fans to run at a maximum of 50%.