Guilty.
My whole way of thinking is basically a dialogue....one persona will have ideas, the other will question them, the first will reconsider and submit an amended idea, etc. I don't have a split personality, I know it's all me really, just that my mind works by critical dialogue with itself.
I often have difficulty in following my thoughts clearly if I remain mute while thinking, and voicing the thoughts helps me to focus on what I'm thinking. Therefore I talk to myself whenever I think I can get away with it. I do a lot of muttering which I just hope is socially acceptable.....I think there's a level of quiet muttering that isn't seen as all that wacky.
Rehearsing future communications seems to be more taboo, and unfortunately I do a lot of that - loads of stuff, and I'll probably never need to use most of it in actual dialogue, but it's good to have it just in case.
I've also noticed that I talk to myself for hours if I'm stressed out or excited by newly-discovered possibilities concerning the ambitions I care about. I guess it's just the usual "racing mind" that lots of people experience when the adrenaline's flowing, but in my case I say it all out loud if I don't think I'll be overheard. It's very hard to stop the process.....best thing I've found is to try to focus on some art, to try to shut down the logical part of my brain. But my logical side doesn't give up easily. It's as if it's really urgent to get all those thoughts voiced and examined before I lose them....they seem incredibly deep and important thoughts at the time, like I've just been plugged into the oracle of the gods.