Buzzing, Clicking, Vibrations in the Hypnagogic State

I know I can attest that when you are nearing what is called the 'Hypnagogic state' - the state of being between asleep and awake - you can start to feel odd vibrations and sound within your head. From all of the literature I have read on the subject of Astral Projection almost all sources state that this state is the crucial moment to leave the body.

Many times this is preceded by sounds in the head - a kind of buzzing sensation that feels oddly like someone is stretching a rubber band from your head and plucking it with a sudden feeling of falling back on your pillow. There are other cases where people hear a sound like chimes or bells just at the moment of unconsciousness. Others hear things like 'horrendous gushing sounds', 'weird ringing/buzzing noises', 'rushing to roaring up to sounds in the upper frequency scale like whistling', and 'very low hum, like a fog horn'.

William Buhlman in the link above says this is a normal state when you start entering a vibrational state just before an OBE. Erin Pavlina also notes this:

"When you feel that tingling sensation all through your body, and you hear the high pitched whine or ringing in your ears, that is what – I mean, I’m not a physicist – but what I believe is happening is you’re raising your vibration, you’re raising your frequency and you’re falling out of phase with your body. So, your spirit, your soul, your consciousness is pulling and separating away from your body, which is at a much lower frequency – a much lower density. 

Now, what generally happens from this place is people get scared or they get freaked out and they simply don’t move. This can also happen during sleep paralysis, which is where you wake up but you cannot move at all. You can see, but you can’t move.
This is actually the moment when you want to try to astral project, because what’s happening is when you feel the tingling and when you hear the ringing in your ears, you have already separated from your body."