Let's say you've heard someone say "A voice in my head narrates thoughts". What happens next inside your head?
I, for example, may produce something like the following sequence of internally represented words and non-words "A voice narrates... [imagines what it can feel like] Does it feel external to [non-verbal reference to conversation partner]? It doesn't work like that [implied reference to myself] [pause for introspection] I produce words. It's not like someone else narrates thoughts in my head. [stop producing words to check that] I just think, and one thing leads to another and that's why it's hard to stop the sequence of the words being produced by me and it's not because I can't stop some intrusive voice inside my head" and so on and so forth.
Phonetic realization of the words isn't important if I don't specifically concentrate on it.