In Morse code! https://www.youtube.com/watch?v=r475OdqBFKA (https://www.youtube.com/watch?v=r475OdqBFKA)
The author has 15 minutes at 15wpm, 20, 25 and 30.
Gil.
I love it. I converted a few chapters of a book to Morse at various speeds and put them in my iPod.