this happened to me once and it wasn't like it was part of the dream, I could literally hear it while unconscious and I think I was dreaming
I think it would be cool to try this again with something that is more subtle and wouldn't wake me up and then see if it has any effect on my dreaming
I could try this with audio files of various scenarios and see if that helps me to dream of that particular subject, like I could play field recordings of maid cafes and some Japanese woman speaking to me softly and obediently .... (XO________OX) maybe I could play happy and positive recordings and that'll help motivate me
There are probably people who do this with hypnosis recordings, I'm sure some trannies have done this to make them feel more feminine.