This thing again. I remember when this first went around the internet a few years ago. I was indeed shocked to learn that people actually hear a voice/monologue in their head narrating their day or whatever.

I always thought it was just a lazy trope used in movies and tv to help explain the plot.

The only time I have anything close to that is if I am actively trying to rehearse what I want say in my head. Then I hear my own voice.