Did they use the 'Miracle Ear'?

When the punks almost run over Alan Ladd in the crosswalk, they are already half a block away, in a speeding, closed car, when Ladd says, "You stupid idiots"(and not terribly loudly). Whereupon the car slams on its brakes, throws into reverse for half a block, and Punk #1 jumps out and exclaims, "Who you calling a stupid idiot?!"

If not the Miracle Ear, they musta had some kind of infra-red night-vision binoculars and the ability to read lips. Those were some sensitive punks!