Shadow People Reports Could Be Caused by Infer Sound

The exact resonant frequency of the human eyeball is apparently debated. Nassau estimated it to be 18 hurts, which was very close to the 19 hurt standing wave that vick measured. In areas where there are infer sound frequencies in this range, whether caused by mechanical equipment or other things, may unknowingly have their eyeballs vibrate. This could explain some shadow people reports. i think some shadow people encounters may be naturally caused by infra sound.