If you go check out the Lucid Dream or Sleep Paralysis sub you'll see there's tons of people who experience the buzz/hum/static sound as they go into sleep paralysis. A lot of the people who can't naturally LD say when they 'practice' that first of all they hear the hum, then they get triggered into SP then when the SP is over they go into LD. I naturally LD all my life and I've never had to go through SP to get to LD, for me they are both standalone things but they come under an umbrella term of Hynpagogia which includes other things such as visual/auditory/sensory hallucinations (totally different to what you get with SP) and things like false awakening come under the umbrella term too.