I like this analogy. I have an internal voice, but "hearing" this voice is very different from hearing a voice spoken out loud and registered with my ears. Likewise, when I'm visualizing a pretzel, the way I am "seeing" it is more of an internal, mental process than when I see things by processing the light hitting my eyes.

Yet other people claim to not have an internal monologue (including my wife and brother) and say they don’t hear anything when they think to themselves, and don’t really even “think” in words for that matter. So this comparison is also tricky because not everyone agrees on either of them. I have a weak visualization ability and strong internal monologue, I’m not sure if they’re correlated in some way or not.