How Infrasound Sneaks Into Everyday Spaces (Image Credits: Unsplash)
Visitors to old buildings often describe an inexplicable sense of agitation or dread, especially in basements where the air feels thick with unease. Researchers now point to infrasound – low-frequency vibrations below the range of human hearing – as a likely culprit behind these sensations. Published this week, a study in Frontiers in Behavioral Neuroscience demonstrates how such sounds elevate stress hormones and sour moods, potentially demystifying reports of paranormal activity.[1][2]
How Infrasound Sneaks Into Everyday Spaces
Infrasound refers to sound waves under 20 hertz, too low for most people to hear consciously. These vibrations arise from common sources like aging water pipes, ventilation systems, traffic rumble, and even wind turbines. In urban settings or older structures, mechanical hums and drafts amplify them, particularly in enclosed areas such as basements.[1]
Animals detect infrasound readily and often flee from it, prompting questions about human sensitivity. Previous field observations linked it to discomfort in reputedly haunted sites, but controlled tests remained scarce until now. The new research fills this gap by isolating its effects on people unaware of its presence.[2]
Researchers Test the Invisible Vibrations
A team from MacEwan University and the University of Alberta recruited 36 young adults for a controlled experiment. Participants listened to five minutes of either calming instrumental tracks or unsettling horror-themed music. Hidden subwoofers delivered 18-hertz infrasound at moderate volumes – 75 to 78 decibels – alongside the audio in half the sessions.[1]
Saliva samples measured cortisol levels before exposure and 20 minutes after. Questionnaires captured mood shifts, including irritability and interest in the music. None reliably detected the infrasound, with guesses no better than random chance. This setup ruled out conscious awareness or expectations as confounders.[3]
Stress Hormones Spike, Moods Turn Sour
Exposure to infrasound raised salivary cortisol significantly, regardless of the music type. Statistical analysis showed a moderate effect size, with levels climbing in the infrasound group compared to controls. This rise persisted even after accounting for self-reported fear or irritation.[1][4]
Participants reported higher irritability, lower interest, and appraised the music as sadder. These negative shifts held across both calming and tense tracks, suggesting infrasound acts independently. Random forest modeling confirmed cortisol and sadness as top predictors of exposure.[5]
Senior author Rodney Schmaltz explained the broader pattern: “Infrasound is pervasive in everyday environments, appearing near ventilation systems, traffic, and industrial machinery. Many people are exposed to it without knowing it. Our findings suggest that even a brief exposure may shift mood and raise cortisol.”[2]
Linking Low Frequencies to Haunting Lore
Historical cases bolster the connection. In 1998, engineer Vic Tandy traced ghostly apparitions in a lab to a fan emitting infrasound, which ceased once removed. Earlier work by psychologist Richard Wiseman at sites like Hampton Court Palace found people sensed odd presences in areas with unusual magnetic fields, humidity, and lighting – environmental quirks that often coincide with infrasound sources.
The current study echoes these anecdotes. Schmaltz noted: “Consider visiting a supposedly haunted building. Your mood shifts, you feel agitated… 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.”[2][3]
- Ventilation and air conditioning units
- Rumbling traffic or nearby roads
- Aging plumbing in basements
- Industrial machinery
- Wind across building openings
What This Means for Health and Skepticism
Short bursts of cortisol promote vigilance, an adaptive trait against unseen dangers. Yet chronic exposure – from constant urban noise or faulty home systems – could fuel ongoing stress, anxiety, or sleep issues. Co-author Trevor Hamilton cautioned that prolonged elevation harms mental and physical health.[5]
Future work should probe varied frequencies, longer durations, and diverse groups. Larger trials might inform building codes or noise rules. For now, the evidence challenges supernatural claims, offering a grounded view of why some places unsettle the soul – or at least the body.[2]
Next time unease creeps in amid creaky floors, check the pipes. Science suggests the spirits might just be vibrations all along.