There's no doubt that wolves and gliding propeller-less planes can be very quiet. But just because those threats are very quiet, there's no point in further reducing your SA. Earphones may or may not have contributed to the wolf attack, but a wolf should not be unexpected in the wilds of Alaska. OTOH that guy on the beach was just running in the wrong direction; it's fairly unusual for a plane to land on a beach in NC. Stuff happens, but that's no reason to let down your guard and go condition white with your SA.