Assuming you're literally talking about subvocalization, it depends on what I'm reading (I do it more with poetry than with academic papers), on how quickly I'm reading (I don't do that as much when skimming), on whether I know what the author's voice sounds like (in which case I subvocalize in their voice -- which slows me down a great deal if I'm reading stuff by someone who speaks slowly and with a strong foreign accent e.g. Benedict XVI), and possibly on something else I'm overlooking at the moment.
I do not notice that I am subvocalising when I read, even when I am looking for it (I tested this on the wiki page that you linked to). I do notice, however, that it mentions that subvocalising is often not detectable by the person doing the subvocalising.
More specifically, if I place my hand lightly on my throat while reading, I feel no movement of the muscles; and I am able to continue reading while swallowing.
So, no, I don't think I'm talking about subvocalising. I'm talking about an imaginary voice in my head that narrates my thought processes.
Hmmm... ...
Another month has passed and here is a new rationality quotes thread. The usual rules are: