Michael Bywater puts it like this,
Wandering from room to room is someone with an iPod; music no longer requires going out, being with other people, or even sitting in a room on your own, listening. Now it is a permanent distraction, a matter of right, a way of affirming your identity without having to be identified by other members of your chosen tribe; even when we interact with the outside world, reluctantly, our ears are plugged with the iPod buds, trickling music into our minds. Our grandparents would have thought it an appalling rudeness; after all, what does it say but, 'I do not acknowledge your existence. You are superfluous to me. I may be moving in the same physical space as you, but don't expect me to acknowledge it.'