Product review (5 stars): Solved Noise Problem
We had two flapper style vents that made noise. One was for the dryer and the other for the bathroom fan in the 2nd floor wall located above the attached garage roof.  When it was windy these vents would make a racket as the wind lifted and dropped the flapper.  These vents solved the noise problem completely.  They are considerably larger but seem to work great.
There is a kit available (not through Amazon) for use with fan vents which consists of a spring that makes the moving component of the vent lighter and easier for the fan to push.  This is mentioned in the instructions that come with each unit and costs about $6 from the manufacturer.  I didn't get this and the bathroom fan vent seems to work fine.
I would recomend this vent especially to solve a noise issue.