If visualizing words at listening speed helps you read faster, you're probably reading pretty slowly.

One key technique in beginning speed reading is to stop subvocalizing the words, so that you can go faster than speech.

Hi. I'm founder of Readlax. There is good exercise to block subvocalizing, it's read text by Readlax chrome extension and at the same time counting from 9 to 1 (9,8,7,6,5,4,3,2,1). It help u read by eyes and block subvocalizing. This technick train brain. We will add this exercise in next release of Readlax Extension

What is done instead of subvocalizing the words? Everytime I look at a word I instantly "hear" it, my imagination isn't good enough to conceive of what could replace that internal experience.

The purpose of the written word is to help you think the concept.

You can read faster if can see the wordand think the concept rather than mentally sounding it out:

    abcdefghijklmnopqrstuvwxyz  

did you really vocalize each letter, or did you just think the concept, "alphabet"?

   alphabetically 

rather than "al-fu-beh-ti-cully" just the concept of "a-z order".

You can also see groups of words at a time:

    The end of the road

and think the concept instead of thinking each syllable.

Isn't being more familiar with words a good thing? Another thing that seems to help is keeping a boring old deadwood dictionary next to my favourite armchair.