Any ideas on how to muffle a bathroom type vent fan? I tried it out
at the store and it wasn't too bad, but after getting it installed at
home, this thing is almost deafening. The drone of this is incredibly
obnoxious.

What I suspect is the problem is that in the store the fan was setup
to push into a "dead" duct, so there was little air movement and thus
little noise. Now in my installation at home, there is a lot of air
moving and also a lot of noise.

For reference - fan is 8" with a baffle rated at 180CFM and 6.5
sonnes. Can I place some sort of smooth venturi type restriction in
the exhaust side of the fan to quiet this down a little. I don't need
this much airflow.

I installed it to draft warm air up the staircase and to stuff it into
the attic. Before I used to alway open the attic access door and let
the attic vent fan draw air as it needed. This worked fine, but the
attic access was in the closet in our master bedroom, neccessitating
leaving doors open and the hazard of loose insulation ending up on the
clothes in the closet.

It accomplishes the desired effect of cooling the house(quite well
actually), but the noise isn't tolerable. I have it wired in parallel
with the thermostat switch for the attic fan, so it only runs when the
attic starts to get to warm but it needs to get muffled somehow.

Ideas?

JW