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Of course he heard them!
He's literally standing 6 feet and 10 1/8 inches away from them!
???: Alright listen here! I'm not sure who you two are, or if you are Lipidus and Squirreline just messing with me, but I DON'T APPRECIATE IT!!!
???: TAKE THIS!!!! AHHHHHHHHHHHHHHHHHH!
He missed them completely. Didn't even get close.