I have a problem with my bathroom vent. It vents directly through the exterior wall of my house and has a small plastic "flapper" to keep air from going in when the fan is off. The problem is I live right near the shore of Lake Erie and the wind coming in off the lake is rediculously strong and on windy nights it makes the "flapper" bang back and forth constantly. It makes a terrible racket. I've checked out the wall caps they have at local hardware stores and they all seem to have the same basic design as the one I already have. So short of planting a tree outside I'm stuck. Has anyone else had a similar problem and come up with a solution?