I understand the embarrassment what a chock to wake up like that! I’m sure he was just as confused as you for a while because his first thought must have been “oh, she was watching porn!” After realizing it was audio I bet his mind was spinning like “she was... listening to porn?” So if the title of the video wasn’t obvious hypnosis, he could be thinking you were listening to some kind of erotica is my thought. few people have heard of NBE, even less NBE hypnosis so my guess is that he’s trying to understand what it even was.
I’m hiding NBE for my boyfriend as well so I can relate to the panic (I have ran to the bathroom with my noogling cups on when he came home unexpectedly) but as a wise person once said on this forum, I believe all men can relate to wanting a part of your body to be bigger. it has even been suggested that some men might find NBE something of a turn on, which is hard to see from our perspective as there’s a kind of “shame” in not feeling big enough. I think the shameful feeling you have is more that your were caught so off guard. I hope you’ll have a good talk and be able to laugh about it soon!