You can't hear it, yet this sound may explain paranormal experiences

Infrasound is very low-frequency sound, below 20 Hertz (Hz), which humans typically can't hear. It can come from natural sources like storms, or from anthropogenic sources like traffic. Some animals use it to communicate, while others avoid it. Scientists investigating humans' ability to sense infrasound determined that we can't detect it, but we do respond to it: it's linked to increased irritability and higher cortisol levels.