Interesting observations. If I understand properly, it seems that some type of delayed processing is happening, which would not be such an unusual occurrence for someone with early onset hearing loss. Perhaps both this young lady and her father are using other cues, e.g., visual, to process and that even thought they don't "hear" what is being said, they are still able to process.
For the second part of the question, I remember discussing this exact phenomenon in a class with Dr. Chuck Berlin. Apparently the efferent (I believe) auditory system responds differently, or is more sensitive, after being "deprived" of sound (such as after sleeping for the night). As the system is bombarded with sounds, there appears to be a type of suppression. I may not be explaining this completely correctly, but I remember we did an experiment where we set the volume of the TV or radio to a comfortable level just before going to bed to see how we would react to that volume setting in the morning after resting. Turns out just about all of us had to turn the volume down in the morning.
Just some shots in the dark, as it were.
Harriet B. Jacobster, Au.D., CCC-A, FAAA
Board Certified in Audiology
IHAER - Institute for Hearing Arts Education & Rehabilitation, LLC