I’ve always struggled with “saying” the words in my head (it’s call subvocalization). I see the word and I automatically “speak” it.
Subvocalizing limits you to about 5000 words per minute—which is still ten times faster than a “fast” reader. In the speed reading course it was a wall that some could not get through. It was explained to us like this—when you see a stop sign, do you have to say “stop” to yourself before understanding it’s message? No your brain understands it without “hearing” it. I think subvocalizing is a remnant of how we first learned how to read—reading out loud. When we were taught to “read to ourselves” we just thought the words. If you hold your throat while you read, you can feel the muscles working away.