Because of all this background noise the person needs to focus their attention on the book (part B) and when the story is sufficiently engaging succeeds in focusing to such an extent that the ‘thought bins’ associated with the story produce a larger signal than the background noise; so much so in fact that if one of the adults were to try to talk to the person in this focused state they would find it necessary to raise the volume of their voice considerably. We have all experienced this at some time or another in a variety of situations, for example reading a food label in a noisy supermarket, trying to hear an announcement in a noisy airport and so on.
We’ve found that when fully engaged with a story, it’s easy to experience the sensations and imagery associated. This is because interfering thoughts and sounds are reduced in amplitude by the narrow focus on information relevant to the story.