Actually in ZombiU the Prepper is talkig to you via the Gamepad. That also means, you only hear him on the Gamepad-speakers, while other sounds come from the TV. He does not comment on much, at some places he drops a comment, aside from that it's more his instructions. But I could think that a future game might extend on it and the gamepad is talking more to you. Like Kid Icarus:Uprising, that consisted of nearly constant talk.