My experience has been that my helmet whistles louder when I an on my CB compared to my supermoto, so I think it's just how the air is flowing around my helmet. When I cover the vents above the face shield, the whistle stops. A bigger screen may stop this as may a different helmet. I was thinking I might buy a new helmet, but mine is still fairly new and find it comfortable, so a different screen may do the trick at a lower cost.