Its interesting that you mention ringing, I had an experience like that a while back. I'm definitely not an advanced lucid dreamer, I have yet to have one on purpose, but I have had 15 or so naturally since I was a kid.
Whenever I'm really tired, just as I'm drifting off I start to hear a faint ringing. It was always a pretty natural feeling and never really came to my attention though.
Except for one time... I was in bed, super tired, wasnt trying to LD, just wanted to fall asleep. Every time I would start to drift off I would get a ringing that quickly increased in volume over 5 seconds or so until it was deafening and startled me back to consiousness. It happened about 5 times before I finally fell asleep.
I'm not sure how long I was asleep but I started dreaming. I was having a dream that I was with Sam and Dean winchester from the show Supernatural. We had a demon trapped in a devils trap and I was standing right at the edge of it. Somehow the demon stood up and pulled out a blade and stabbed me.
I was faintly aware that I was dreaming so it didn't scare me but right as the demon stabbed me the ringing started along with intense vibrations and the ringing increased in volume until it was so deafening that it woke me up.
I tried to fight it because the demon stabbing me made me fully lucid for about 5 seconds until the vibration and defending ringing woke me up. Its almost like the vibes and ringing somehow sucked me out of the dream.
I'm not exactly sure why it happened but I just wanted to relate my experience, my theory is it has something to do with Rem cycles kinda like the vibrations and sound during WILD, I think I involuntarily WILDed that night, thats how Ive had a couple of my lucids when Im REALLY tired, its like my body falls asleep before my mind has a chance to and i enter straight into a dream. But like I said I'm no expert