Why do you hear your own voice differently to other people?

I think what she's getting at here is that if you listen back to a recording of yourself you sound subtly different to how you think you sound. When you listen to a person speaking, the air transmits the sound, goes into my ear and wiggles the ear drum and the bones of the middle ear and eventually makes electrical impulses. When I hear myself speaking, the sound not only goes through the air but also through the bones of my skull. So when my jaw is moving I'm making the bones vibrate directly, and therefore it sounds different. That's probably the explanation.