You can "listen to" an orchestra without being able to discern each violin. You can "listen to" the wind in the trees without hearing a single leaf tapping agai

You can "listen to" an orchestra without being able to discern each violin. You can "listen to" the wind in the trees without hearing a single leaf tapping against a branch. There's no suggestion that the user would be able to understand every single AM broadcast; it's just a way to get a sense of the "oeuvre" of the entire (covered) radio band.