The voice in my head is me. Sometimes if I watched a movie or talked to someone, the voice might sound different but it's still me. It doesn't talk to me, I talk with it. It's as if I was speaking out loud, but only I can hear it. Look up subvocalization. This voice in your head is so much like talking that you make some larynx movements to match the words.

Visualization, or seeing things with your mind's eye is similar. The closest metaphor I can come up with is if your regular perception was the main monitor of your computer, subvocalization and visualization would be the monitor and speakers on the side. It's doing its own thing without taking away from the main monitor, and you can focus on it (zoning out), and for some people it's higher res or higher quality than others. For you, there is only the main monitor and set of speakers. In this metaphor, there is nothing outside of the monitors and speakers in terms of perception.

Some examples of what my stuff works like: When I remember something I saw, it "plays on the second monitor". Having a song stuck in my head is like having the "second set of speakers" play the song on repeat. If I say "this sentence is narrated by Morgan Freeman", then my inner voice now sounds like Morgan Freeman. If I want to visualize anything, I "turn to my second monitor" and the thing is there. It can be still or animated, black and white, 2d or 3d, I can do it. I can't do 4d or anything like that.