Harry is on standby, waiting for any new developments on the brownie search, when Aurora alerts him to the squeaks from the walls. So he walks up to the wall and presses his left ear to hear the noises.

At the same time, he doesn’t try to talk too much that would inform the brownies of any new information they might have the moment he sees Aurora’s signal not to say anything. What is the reason why the brownies and dust bunnies are making a ruckus in the houses?