Well, My wife loves to cook in the trailer (and I love to eat).  However, the range hood fan was too loud, in our little 19' trailer.  I looked into sticking in a 12v computer-type fan, but too many modifications were involved, without checking other possibilities.  Maybe a fan-speed control?  I  wasn't sure on messing with reducing the 12v DC current, and possibly toasting a motor.

   So, I pulled the fan out, turned it on, and darned if it wasn't kinda quiet, while holding it.  That got me to thinking about isolating the fan bracket and fasteners from the vent hood.  I stuck some 1″ wide rubber pieces that I had, between the fan bracket and the hood, making sure that the bracket didn't contact the vent hood anywhere.  I also cut a couple rubber pieces to isolate the two fastener screws from the bracket and the vent hood.  Then I tightened everything up & reinstalled the vent filter.

   I do notice that it is quieter.  It isn't perfect, but anything that moves air has to make noise.