I usually scream in a high-pitched monotone voice whenever I read, mainly so I don'y get confused. Annoying everyone in a 30 foot radius from me is just a bonus.
Seriously, tho, if I'm reading something, I'll hear a voice that sounds kind of like my own, but a lot of times I like to pretend a different person is reading. Like, if I'm reading Go Dog, Go! I'll pretend Barry White is reading it. When I was reading The Fellowship of the Ring, Meowth was narrating it. And now whilst I'm reading The Hitchiker's Guide to the Galaxy, I hear Lister from Red Dwarf talking. Or Kryten and Rimmer.
My mind is a strange and/or fascinating place, if you're me...