Product review (5 stars): It was like a turbine engine when actually installed
It was whisper quiet when I hooked it up in the living room to test function.  It was like a turbine engine when actually installed.  I followed the manufacturer recommendation of a T-top vent cover on the roof for my 7 inch exhaust duct... this helped significantly.  Lessen learned:  the ducting needs to allow air flow. The duct cover needs to allow air flow.  Otherwise, its noisy