Many people have learned how to PhotoRead only from the book. If you are disciplined it will work for you.
The audio course is good for people that want to be guided while learning how to photoread. Paul Scheele guides you through all the steps... However, it's all in the book anyway. Being guided while you photoread, or listening to the relaxing sound of the ocean while you relax, following Paul's words, is of course beneficial, but not essential.
There are a few things that are not in the book, like the "star of wonder" exercise or articles provided for practicing photoreading (with questions to test comprehension, etc.)-but again that's not essential.