I think German Sheps go deaf on their own. I could be wrong but I've heard talk about them having some genetic tendency. I guess like how labs have the hip thing.
Talk to some bikers, they ride with the wind in their face all the time... if hearing loss is common to them, you'll have your answer. Then again a bike is friggin' loud too. Good question bud. My dogs too much of a princess, thing wont go near an open window in the truck, she wont go near a dead duck in the water either.