I definitely think out loud and I know it drives a lot of people crazy.
I just did it to one of my leaders at work. I do it to my wife constantly and if we're friends and you've never noticed me doing that to you, um... you're lucky?
And yet, when I try to come up with an idea or solve a problem, I often sit down on the sofa and just try to think. Usually, the more complex the issue, the more I stress out and isolate myself. But instead of picking up a pen or the keyboard, I try to muscle through it without actually using any muscles.
This is dumb.
When you write, it's like thinking out loud but it's better. I'm doing it now. I'm telling my screen what I think. And then I'm reading what I think, tweaking the thoughts that I can now see with my eyes. Something something neuroscience. It sure works. And I'm trying to turn it in to a habit.
I was at a conference and heard Cameron Moll, an internet hero of mine, speak and give us a generous Q&A session afterward. I asked him about the writing and why he did it and what it had to do with the work he's famous for - building amazing websites and creating ridiculously awesome letterpress posters. I wish I'd written word for word what he said, but he called writing and publishing his blog one of the most transformational parts of developing into the type of professional that he wanted to be.
Sorry if this is meta...
... and obvious, but I recommend you take Cameron's advice. I plan to. If you want to do anything well, you need to be a clear thinker and a hard worker. And writing builds both skills.
Thinking with your fingers on the keyboard, even when you may not feel like you have anything to say, and teaches you what you believe and teaches you that you should try it again tomorrow.
Talking may be one way of thinking out loud, but writing forces you to refine your thinking and leaves you a time capsule of what it was that you thought, even as it changes over the days, weeks, months, years.
Bonus:
Go read Cameron's interview on the Great Discontent.