The most we use during PhotoReading and activation is nature sound. Nothing is necessary because the photofocus quickly switches on the correct brain state. I don't recommend any because you need to know the section of the entrainment soundtrack that is most ideal and you might still be using the alpha section when alpha is the last thing you need while PhotoReading.
Even beginners are able to get the ideal PhotoReading state by just softening their focus and flipping the pages with a steady rhythm. So setting up audio for PhotoReading is an unnecessary procastination device.
Consider, finding the CD, CD player and headphones, replacing the batteries and not to mention the wires in the way while you're flipping pages. Sure once it's set up it only takes about 20 seconds and yet 1.5 to 3 minutes is all that it takes to PhotoRead a book. Many people will put off PhotoReading when everything isn't right. That's pointless. Paul has had his students PhotoRead in the middle of a busy intersection just to show, use the tangerine technique, soften your gaze, say the chant and flip the pages with a steady rhythm and you're done with PhotoReading in the minute to 3 that it takes to PhotoRead the average book.
Alex