In the story, we can find various actions performed by Jack and Annie. Let us learn some of the following actions related to the mouth.
To speak very quietly using the breath so that only the person close to you can hear you
Grandmother sat down and sighed deeply.
To speak with pauses or repeated sounds
Peter stood in front of the teacher and stammered his reasons of being late to school.
To take a short quick breath through the mouth especially because of surprise, pain or shock.
Source: Cambridge Dictionaries Online, Collins Cobuild Advanced Learner's English Dictionary