I believe that that sound is a signal from alien, in which is information we cannot
understand, but the subconscious does, or the brain resolves it during the sleep.
I've seen indications of this. Well, not aliens, but I've noticed that the ringing in my ears became intelligible sounds when I went into a trance.
I have wondered the origin of this sound. I have read where they say you can follow the sound back to the source. I taught one person to have an OBE with the use of this sound. She traced back the sound and traveled through a tunnel and saw the light at the end. Maybe this sound is a connection to the afterlife.
i dont know about all of that now, but it is nice to believe
everytime it rings in my ears i just stop. it feels so weird