More from the article ...

... "Consider visiting a supposedly haunted building. Your mood shifts, you feel agitated, but you can't see or hear anything unusual," says the study's senior author Rodney Schmaltz, a psychologist at MacEwan University in Canada.

"In an old building, there is a good chance that infrasound is present, particularly in basements where aging pipes and ventilation systems produce low-frequency vibrations," Schmaltz continues.

"If you were told the building was haunted, you might attribute that agitation to something supernatural. In reality, you may simply have been exposed to infrasound."

Any sounds below the threshold at which humans can consciously perceive them -- around 20 hertz or lower -- are considered infrasound. These sounds have a remarkable ability to travel past obstacles without dissipating, so their influence is wide.

They can be generated by old pipes and machinery -- hence the haunted building link -- but also emanate from natural sources like storms, earthquakes, volcanoes, and aurorae. Some animals even incorporate infrasound into their communication and navigation. ...