I’m not sure exactly which fields are counted as permanent physical changes. It’s a bit unclear to me too. I think it may apply to fields like Grow Taller, Facial Symmetry, White Skin Genetic Change, Diabetes Treatment, Endocrine Rejuvenation and Anti Aging.
It seems hormone audios aren’t what @SammyG means based upon his earlier post. It may be something they intend to clarify further in the FAQ.