Wow. I've never been able to articulate this experience, but it is something I find very jarring. It's jarring for me to see people behave outside of their usual persona. A favorite teacher of mine once had his young son in class for some reason. The class was normal except for when the son started playing with something he shouldn't have. The teacher snapped at the son with such anger and fear.
I had never seen the teacher behave this way and it was deeply upsetting at the time.
A different region of the brain is active while singing vs speaking. There are also physical difference between singing and speaking that prevent stuttering, such as: controlled breath, memorized lyrics, and longer phonation.
I had never seen the teacher behave this way and it was deeply upsetting at the time.