Writing Craft: How Point-of-View Affects Dialogue

Here's the latest from Jami Gold, Paranormal Author :

With all the chaos in the world, my concentration is shot as far as writing. Im probably not alone.

Luckily, my readers are helping me out with questions that I can use for topic ideas. *grin* (So keep the questions coming!)

Eshaani asked:

My questions are:

1. Is it a change of POV when two characters are talking & one of them reacts to what the other said, but not loudly, not even physically (just a comment of scorn or disbelief but...