The mind evolved to comprehend spoken words before written words.
I know the book gave the advice to eliminate subvocalizing, so it might have not included what I'm about to propose to avoid confusing the reader, but I think the author missed the mark by not adding the advice of practicing saying out load what you are reading - trying to inflect tonality, mood, pacing, etc etc to what the reader thinks the author is speaking through. Not only does this makes unfamiliar words an audible stimuli and making it easier to say later, but to try to get in the head of the author. It's almost like acting! A practice I've come to realize is of utmost impprtance to self-development ^~^