For over two years I've been riding down the highway listening to the wind racket around the rear doors sounding like the windows were down about a half inch. I posted this irritant on another forum recently and got an answer in a couple of days.

There is a U-shaped seal in the piece between the rear door window and the stationary quarter window that the main window travels in. That seal slipped down about an inch or so and allowed wind noise to intrude around the edge of the glass. I pulled the seal back up into position and the noise stopped. I'll stick it in place with a dab of RTV so make it stay put.