AirScape fans are extremely quiet for their power. However, if you have the attic space, there is a nice trick to reduce sound levels even further. The Acoustic Plenum Box adds 12 inches to the total height of the your AirScape installation and can reduce operating sound levels up to 3 dBA.
Insulated 12" raised-frame 24 gauge thick galvanized sheet metal construction with 1.5" of acoustical insulation. Ships flat and is easily assembled. The kit includes insulated raised frame and installation hardware.