There is more than meets the eye…or ears…
Many of us have walked into an old building and felt some kind of eeriness. Depending on your own personal beliefs, you might be inclined to attribute this feeling to the presence of something supernatural. But science has found another culprit that haunts our psyche in these places, and it’s not ghosts.
Researchers at MacEwan University in Edmonton, Canada, found that when people were exposed to infrasound, which is typically imperceptible to humans, they still experienced a rise in cortisol levels and irritation.
“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,” noted senior author Rodney Schmaltz.
Therefore, many people who notice a mood shift in a place regularly defined as “haunted” might attribute that agitation to something supernatural. In reality, the infrasound waves are to blame.
How the study worked
The study, published this year in Frontiers in Behavioral Neuroscience, randomly assigned 36 participants to one of four groups. Each group would listen to either “calming” meditative music or “unsettling” horror-themed ambient audio. Each group would also be near hidden speakers playing infrasound between 75 and 78 decibels, a range consistent with what mechanical systems commonly produce inside buildings. These speakers were turned off and on once throughout the study.
Each participant provided saliva samples immediately before the music started and again 20 minutes later, which were analyzed to measure cortisol, the hormone the body releases under stress.
Researchers found that, regardless of which type of music they heard, the participants showed a notable increase in salivary cortisol when exposed to infrasound.
And while anecdotal, participants in the infrasound condition rated themselves as more irritable, less interested afterward, and even described the music as noticeably sadder.
Interestingly, what people didn’t seem to feel when exposed to infrasound was anxiety or fear, but rather irritability, disinterest, and a low-grade emotional discomfort…all of which correlate to a spike in cortisol.
Infrasound in nature
The researcher explained that in the animal kingdom, some species (such as elephants) use it to communicate with one another over great distances. Others, like some birds, detect coming storms from infrasound.
Others still have an aversion to the discomfort it causes. Some fish have tiny stone-like organs in their inner ear that help them stay away from it and remain balanced and upright in the water.
Humans happen to have similar structures, and researchers theorize that this balance system, which connects to brain regions involved in emotion, may register infrasound without conscious awareness.
Still, given the small amount of study participants (as well as the lack of diversity, most were female undergrad students), no major conclusions can be drawn. So ghost hunters, fret not!
Whether you lean paranormal or skeptical, the science does confirm that humans are more sensitive to unseen forces than we realize, whether those forces come from vibrations in the environment or something we simply don’t yet understand. Either way, our minds and bodies seem capable of picking up signals long before we consciously recognize them.
