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Rapid, echoing pops go off in Michael Marshall’s ears when he listens to an Australian Open tennis match, followed closely by high- and low-pitched clinks. Three pops on the left signal that the ball landed close to the line; a low-pitched clink means that the player returned it with a backhand stroke.
Without context, these noises might sound like arcade sound effects or some new version of Morse code — but each one is a message meant to help people who are blind or have limited vision follow the game.