Hearing for cats is like smell for dogs. It's important to them. Your cat would never hear a car driving up behind him or another animal coming towards him. I suggest keeping your cat indoors. If your kitty really does enjoy going out, put a harness on him and tie him outside, keeping an eye on him of course. I once fostered a gorgeous all white deaf cat. He was very sweet but spooked easily because he never knew when someone was coming up behind him. The safest thing for special kitties like yours and the one I fostered is to stay indoors.