I’m not sure I can easily tease out the differences. For one thing, I talk to myself constantly, and answer myself, so as the old saying goes, I’m crazy :) For example, figuring out what to write to you in this moment is a dialogue between me and me talking back as if I am you. You are asking me to clarify if I hear myself talking for you in my own voice or as someone else, and in this case I hear only me — the same voice for both of us. Since I don’t know your voice, I’m merely speaking for you.
But I hear others too, if I know their voice. For example, if I have an upcoming argument ( say a meeting with a boss or colleague and I know I need to make a point and get their agreement), I will start having that argument in my head before the moment itself. Since I usually know the person I will hear them in their voice. I will make my points then “listen” to their counterpoints in an attempt to work out the strategy.
This is not always welcome nor healthy. Prepare one way for an argument and it goes another — then what? Make myself anxious over something that never comes to pass? What value does that offer? I have been trying to refrain from this over the many years but when it does happen, I hear the voices I know.
Now when I write dialogue, I start hearing differences that I am making up. Women, men, boys, girls, people of different nationalities and languages, these all come with characteristics to their voices that are me, only in the sense that I am inventing them. But the more I identify with a character, the more “me” is in there, including word choice.
For example in this story, I have some lines from a young man who is second-generation Pakistani-American. I have worked with Pakistani and Indian nationals for many years, and in my mind, my character’s voice was a conglomerate of what I have heard, then lightened to be almost silent, because he has only lived in the states. But his words and rhythm are entirely mine. I heard him speak as I was choosing what his lines would be.
As I say, your article has led me to examine my mind and process more than I have since school — a few years ago :) So thanks for asking the question. I just learned a lot!