This happens while Ray (Tom Cruise) is talking to the news woman after the plane crash. They're interrupted by the roar of one of the Tripods.
Moments before, Ray was told that the cameraman was deaf. The roar was distant yet the cameraman was the one to say "Did you hear that?" How does a deaf guy hear a faint noise?
The one that said "Did you hear that?" was the 'other' black man (the driver). In that scene the deaf one is the one grasping some things and looking up after the driver says that.
Two things: The one who said "did you hear that" was the other non-"deaf" guy. However, this is still a slip-up because the guy who had gone deaf definitely looked up with the other guy when the tripod siren went off. He couldn't hear Ray yelling to him, but he heard the faint sound of the siren. Definitely a slip-up.