Alien Attack? Mass Hysteria? Conspiracy?

I find it hard to decide where this belongs:

Quote:

Some felt vibrations, and heard sounds — loud ringing or a high-pitch chirping similar to crickets or cicadas. Others heard the grinding noise. Some victims awoke with ringing in their ears and fumbled for their alarm clocks, only to discover the ringing stopped when they moved away from their beds. The attacks seemed to come at night. Several victims reported they came in minute-long bursts. Yet others heard nothing, felt nothing. Later, their symptoms came. http://ift.tt/2jBtWW9

Does anybody have any idea what this is?

via International Skeptics Forum http://ift.tt/2xJs2Jv