Because I heard mixed reports; & I wanted to be careful. In using 'mind programming' which is essentially what this is; I think that you need to be sure of what is happening. I also think that in people that have experienced psychosis, & severe MH issues; then they do need to be careful around any techniques that can alter conscious states; whether that be with drugs; or hypnotism, NLP, Hemi-Sync, or whatever.
in my opinion listening to audio or music has far less potential for negative effects or damage than regular doses of drugs that alter brain chemistry. but then everyone is different and more or less susceptible to different things
(there is no-one speaking to you in this concentration CD, its just music and sounds)