I've always thought with a rather low voice. My speaking voice is low for a girl and usually comes out monotonous sounding, which helps me sound like a guy. So that's cool. Unfortunately when I am excited about something it becomes much more feminine. A lot of the time when I am thinking, I talk to myself out loud, and I generally end up sounding like a younger version of the male voice in my head. Which I think is pretty cool, too. I really hope that T will actualize my thought-voice, when I take it.
I think it's really interesting how some people don't really think in words. As for me, I usually switch around depending on the task that my mind is currently dealing with. If it does not involve speech or any very wordy concepts, I tend to utilize images with small snippets of words. And when I am thinking of different 'philosophies' or concepts of life, or when I am brainstorming ideas in general, I usually end up speed-thinking and unable to correctly remember the ideas later because I didn't think with enough words. What a bummer!