The other day a guy in a big truck was backing out of a handicapped parking space. Right behind him was someone in a small sports car. The guy in the car kept honking but the truck backed right into him. This happened because the handicap the guy driving the truck had was that he was hearing impaired. Seems like it shouldn't be too hard to design a small light that would sit on top of a car's exterior mirrors. The sound of honking would activate it, letting the handicapped driver know someone was behind him. This invention would be a device that could also pick up sirens so if someone was playing their radio too loud with the windows closed they'd still hear/see that an emergency vehicle was coming up fast behind them.