Reading without sub-vocalization is impossible, although you may not notice you are doing it.

Here's the problem with that. You can't read without subvocalization. Carver and Rayner have both found that even the fastest readers all subvocalize. Even skimmers subvocalize key words. This is detectable, even among speed readers who think they don't do it, by the placement of electromagnetic sensors on the throat which pick up the faint nerve impulses sent to the muscles. Our brains just don't seem to be able to completely divorce reading from speaking.

skeptoid.com/episodes/4229