MacEwan University scientists, collaborating with researchers from the University of Alberta, have presented compelling evidence that exposure to extremely low-frequency infrasound from natural and anthropogenic sources may result in some of the physiological changes associated with paranormal experiences.
The research team behind the somewhat haunting findings suggests that understanding how even brief exposure to infrasound from creaking buildings or raging thunderstorms below 20 Hertz (Hz), which is too low for most humans to hear, could help design strategies to mitigate these effects in real-world settings.
Undetectable Infrasound Exposure Can Cause Physical Symptoms
According to a statement announcing the findings, some animals use infrasound to communicate, while others tend to avoid it. As noted, human activities can also result in low-level infrasound.
“Infrasound is pervasive in everyday environments, appearing near ventilation systems, traffic, and industrial machinery,” explained Prof Rodney Schmaltz of MacEwan University, senior author of the study detailing the research. “Many people are exposed to it without knowing it.”
Previous investigations have established that humans lack the ability to directly sense infrasound. However, studies have also shown that exposure to infrasound can increase a subject’s cortisol levels and cause a general sense of irritability.
“Increased irritability and higher cortisol are naturally related, because when people feel more irritated or stressed, cortisol tends to rise as part of the body’s normal stress response,” explained Kale Scatterty, the study’s first author and a PhD student at the University of Alberta.
Professor Schmaltz said his team’s work expands on those findings, suggesting that even a brief exposure to infrasound may shift mood and raise cortisol levels enough to make someone aware that something is happening to them but unable to pinpoint the cause.
Paranormal Experiences and the Haunted House Scenario
As a real-world example of how mood-altering infrasound can generate some of the common symptoms associated with some paranormal experiences, the professor described visiting a supposedly haunted house or building. For example, Schaltz noted that almost immediately, “your mood shifts (and) you feel agitated.” However, the professor adds, “you can’t see or hear anything unusual.”
When searching for a cause, Schmaltz suggested that you may not be experiencing paranormal ghostly forces inveigling you to depart their haunted domain. Instead, he notes, there is a good chance you are in an environment ‘crawling’ with infrasound, “particularly in basements where aging pipes and ventilation systems produce low-frequency vibrations.”
“If you were told the building was haunted, you might attribute that agitation to something supernatural,” Schmaltz explained. “In reality, you may simply have been exposed to infrasound.”
Experiments Show Infrasound Increases Irritability and Decreases Interest
To test their theory, the team recruited 36 participants willing to sit alone in a room. Calming music was played in half of the rooms, while the team played what they described as “unsettling” music in the other rooms. Critically, half of the rooms, regardless of type, were equipped with subwoofers emitting infrasound at 18Hz.
After a timed exposure period, the study participants were asked about their feelings and to rate the music on a scale of 1 to 7. Each participant was also asked whether infrasound was present or absent.
To measure cortisol levels, each participant provided a saliva sample immediately after leaving the music room. As predicted, tests confirmed that participants exposed to infrasound had generally higher cortisol levels, a hormone typically associated with elevated stress and irritability.
When comparing the two data sets, the team found some strong correlations. For example, subjects exposed to infrasound reported feeling less interested in the music and more irritable overall. Those same test subjects also described the music as “much sadder” than the non-infrasound group. Surprisingly, even subjects who experienced increased irritability and less interest were unable to discern if they were exposed to infrasound.
“Participants could not reliably identify whether infrasound was present, and their beliefs about whether it was on had no detectable effect on their cortisol or mood.,” Schmaltz explained.
A First Step Toward Understanding the Effects on Humans
When discussing the potential implications of the team’s findings, the MacEwan University professor said the study subjects’ reactions suggest that the human body can “respond” to infrasound even if they can’t hear or otherwise detect it. The professor said the findings also suggest that even a brief exposure to infrasound may raise cortisol levels and shift a person’s mood, “which highlights the importance of understanding how infrasound affects people in real-world settings.”
Scatterly echoed those comments, while also noting the limitations of the current study, such as the small number of subjects. The researcher also noted that testing was limited to one infrasound frequency, stating that “there could be many more frequencies and combinations that have their own differential effects” on the human body.
“This study was in many ways a first step towards understanding the effects of infrasound on humans,” cautioned Scatterty.
Other highlighted limitations include the collection of subjective reports in participant mood, “without directly observing their responses during the trial.” The team also noted the lack of diversity in the small set of test subjects. of participants. For future efforts, Schmaltz said that testing different frequencies and exposure durations would be the “first priority.”
“Infrasound in real environments is rarely a single clean tone, and we don’t yet know how different frequencies or combinations affect mood and physiology,” the professor explained. “If those patterns become clearer, the findings could eventually inform noise regulations or building design standards.”
As for the impact of the team’s study on paranormal research, the professor said his own research into the field has led him to place more weight on scientific testable hypotheses, such as his team’s approach.
“As someone who studies pseudoscience and misinformation, what stands out to me is that infrasound produces real, measurable reactions without any visible or audible source,” Schmaltz explained. “So, the next time something feels inexplicably off in a basement or old building, consider that the cause might be vibrating pipes rather than restless spirits.”
The study “Infrasound Exposure is Linked to Aversive Responding, Negative Appraisal, and Elevated Salivary Cortisol in Humans” was published in Frontiers in Behavioral Neuroscience.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.