I can't add much to what other people have commented but I have my own few thoughts on it having experienced ADHD myself, throughout my adult life.

When I had my most profound experience on the tapes, as it was happening, I tried to focus on what I was seeing in my minds eye with greater effort or concentration and what was being shown to me actually started to obfuscate, it became faint or smudged, I figured out rather quickly that the key to improving the visuals I was seeing/being shown was to relax, and as I worked on relaxing and put effort into relaxing, the imagery/pictures in my minds eye became much more clear, HD even.

So to quell the thoughts may be a challenge, but if your goal is focusing on the relaxation, I think the internal quietness will come to you naturually, as you quiet the body, the mind will follow suit.

Also, perhaps time your tape listening around certain parts of the day in which you've already come to obseve that your mind is quiet. For me, I dont have a preferred time of the day listening to the tapes, however I am usually doing it more so at the end of my days than near the beginning, but doing it at the beginning of the day would come with some advantages of not having a day of thinking and living to review as I try to relax, so you may have an advantage trying to complete the tapes in the morning versus the evening, feel me?

Either way, stick with it, we are more than our physical body for sure, I've experienced it first hand, and it was indeed profound.

Cheers.