Scientists Investigated a Frequency Linked to ‘Paranormal’ Encounters. The Results Were Unsettling.

Study Links Infrasound to Unease in Paranormal Settings

Unsettling sensations in so-called haunted locations may stem from exposure to infrasound—low-frequency sound waves below 20 hertz—according to a study published in Frontiers in Behavioral Neuroscience. Though inaudible to humans, these frequencies appear to induce stress and negative emotions, offering a potential explanation for reported paranormal experiences.

The Experiment

Researchers at the University of Alberta and MacEwan University conducted an experiment with 36 volunteers, exposing half to 18-hertz infrasound while they listened to calming or unsettling music. Participants provided saliva samples to measure cortisol levels—a biomarker for stress—before and after the sessions.

Key findings included:

• Elevated cortisol levels in those exposed to infrasound, indicating a physiological stress response.
• Participants reported increased irritability and perceived the music as sadder when infrasound was present.
• No conscious awareness of the infrasound, suggesting subliminal perception.

Natural and Human-Made Sources

Infrasound occurs naturally during events like volcanic eruptions, storms, and avalanches, leading researchers to theorise that humans may have evolved an aversion to these frequencies as an early warning system. However, modern sources—such as industrial machinery, wind farms, and traffic—also generate infrasound, potentially contributing to discomfort in urban or “haunted” environments.

Previous field experiments, including tests at the haunted attraction Deadmonton, found that infrasound accelerated visitors’ movement through the space, reinforcing the link between these frequencies and unease.

Limitations and Future Research

The study’s small sample size (36 participants) was constrained by the cost of cortisol testing, but the results provide a foundation for further investigation. Lead researcher Kale Scatterty emphasised that while the findings are promising, they raise new questions about how infrasound affects the brain and whether it could be classified as a form of noise pollution.

“We get very excited when we find something positive like this, but for every question we answer, five more arise.”

— Kale Scatterty, Neuroscience and Mental Health Institute

Key Takeaways

• Infrasound (below 20 Hz) may trigger stress and negative emotions, even though it is inaudible.
• Exposure to 18-hertz infrasound increased cortisol levels and altered mood in study participants.
• Natural and human-made sources of infrasound could explain discomfort in “haunted” locations.
• The study suggests infrasound acts as a subconscious environmental irritant.
• Further research is needed to explore its broader effects on humans and wildlife.