What is sound? We’re told that it’s a wave traveling through a medium, but we don’t hear sounds as existing in the air; we hear them as located at the place where they’re generated. Is sound a quality of an object or of the surrounding medium? “Listening to the birds outside your window, the students outside your door, the cars going down your street, in the vast majority of cases you will perceive those sounds as being located at the place where they originate,” writes St. Joseph’s University philosopher Robert Pasnau. “But if sounds are in the air, as the...