if I remember correctly,Laura said:"Gurdjieff and Hypnosis" discusses that relationship to some extent, though not in depth. The point is made that, at a certain point in time, Ouspensky wanted a demonstration from Gurdjieff about his claimed powers. Apparently, Gurdjieff gave it to him and it was a very bizarre and possibly upsetting experience. It was after that, I believe, that Ouspensky became disaffected.
Gurdjieff caused a Voice to be heard by Ouspensky that emanated from Ouspenskys Own Sternum , or Diaphragm,
Apparently that was a little too much for him.
Yet I have experienced people who can talk into anothers head.
And even on one occasion was able to hear other peoples thoughts, by making completely quiet my own mind.
Havent finished more than the first chapter of the hypnosis book,
But I hope to have something of value to offer soon.