I can't speak for anyone else, and I don't know if I'm having auditory hallucinations or if it's because of my spiritual practices, but... whenever I am exposed to white or pink noise for any length of time, I start hearing voices. Sometimes it's just one voice, sometimes many voices. It's disturbing, and I don't like it at all.

I do have an 'ambient sound' machine w/a couple of different settings - white noise (static), thunder, rain, the ocean... the actual 'nature' noises are soothing, add to my meditations, help me fall asleep. I've also got a CD that's supposed to stimulate the brain's ability to create delta waves for better sleep - it sounds all new-agey with chimes, and I can fall asleep to it, but I don't feel that I get 'better' sleep because of it.