Like real estate -- location, location, location. Riding through woods it can be (figuratively) deafening; half a mile later riding through fields it's background noise.
Cicadas are clumsy, slow fliers, but their shells aren't the hardest. I hit one on my chest, got my attention but I've been hit by worse. Now if you feel something on your sleeve, look down, and see this weird looking thing crawling on you...