Ohhhh, okay – so, if I’m understanding correctly, the source of the sound is sort of “catching up” to the vibrating air molecules it put in motion? It pushes the sound in the air, the same way it pushes the air – the same way you’d feel wind from a passing plane.
Could something else theoretically compress the sound waves of another object? Say, if a plane is flying a few feet above a train at the same speed (as if that were safe), and the train was making no noise of its own (for some reason…), and then the plane stopped moving forward (in midair…no one was injured teehee), could the train have some effect on the sound waves created by the plane?
And…there’s no such thing as a “sound wave”? It’s **just** air, just the atmosphere we know, but vibrating? There’s nothing new being “released” into the air, unlike light?
