Lara has it right. It is over-stimulation.

BUT, you need to understand what over-stimulation is.

The injured brain has a seriously decreased ability to process sensory stimulation. A healthy brain can filter out a vast amount of sensory stimulation that has no current need to be recognized and processed. Echoes, voices from the nearby conversations, background sounds, and much more have no need to be processed so the healthy brain filters them out and ignores them.

Let's say it can tolerate 1000 pieces of sensory stimulation and filter out and ignore 600 pieces. It has no problem with the remaining 400 pieces of stimulation but not much more.

The injured brain loses this filtering out/ignoring function.

Let's say it can process only filter out 200 pieces of stimulation out of the 1000. The remaining 800 pieces of stimulation overload the brain by a factor of 2. It can cause stress/fight or flight chemistry in the brain. For many of us, we can expect to need a few days to even a few weeks to recover from serious over-stimulation.

My neuro did a test that showed how much stimulation made it past the filter. As he said "You hear everything. How do you handle that?"

I wear ear plus in restaurants and in auditoriums. I know I might need to leave.

That has been my condition for over 20 years.