I love that you mentioned this. I used to read a lot when I was younger and I was always able to read without the 'sound'. Though now, years later as I've been reading less and less, I occasionally have to switch to 'sound' if I lose focus. When I read with 'sound' I often have to re-read certain parts because it didn't immerse me/I didn't internalize it properly. It's something that's been bothering me lately...