Hey Vincent,
I think I know what you're talking about. It's called "subvocalization," right?
I learned Evelyn Wood's Speed Reading 7 Day Course a few years ago, and I learned a few techniques as to how to not do this.
First off, a method which didn't help me, but helped a lot of other people is to use that little voice in the back of your head for something else. Try thinking "mmmmmmmmmmmmmmmm" or "aaaaaaaaaaaaaaa" while reading, so that you use your subconscious instead of your conscious. I mean, it is your conscious that makes those sounds of subvocalization.
Also, try reading in groups of words, instead of one word at a time. Use peripheral vision to do this. Try taking in four through eight words at a time. Sooner or later you'll be taking in whole lines at a time. I don't think it's possible for your conscious mind to "subvocalize" about six words at the same exact time as you read. So doing this will help stop that, and you'll get through the text faster.
Also, try to stop regressing. This is when you go back to read something you already read, because you think you didn't "comprehend" it. Reading in groups of words will help stop that. This is mainly caused by saying the words in your head, because if you pronounce it wrong, you think "Oh, that word isn't four, it's pour."
Anyway, try doing this, and soon you'll stop subvocalizing.
Good luck, I hope I could help.
-JackTuff