I think the image here in this person's mind is of someone bumbling around an isle, not looking where they're going (2 people tend to look around more and be more cogniscent of their environment, especially when the sounds they're listening to are coming from the environment (human voice, 3 feet away) and not a small box a few inches away)... and then occasionally yelling, "WHAT?!!?" into the phone when they can't hear.