Post Content A new study by researchers at MacEwan University in Canada has found that while humans cannot consciously hear it, their bodies still sense infrasound, which are sound wave frequencies below 20 Hz. (Photo Credit- Canva)
Picture yourself walking into an abandoned mansion; the first sensation would be thrill, which eventually turns to fear. This fear of the unknown is what most people attribute to supernatural elements often associated with ‘haunted’ spaces. However, what you are feeling might not be what it seems.
A new study by researchers at MacEwan University in Canada has found that while humans cannot consciously hear it, their bodies still sense infrasound, which are sound wave frequencies below 20 Hz. Infrasound falls outside the range of human hearing, yet exposure to it may trigger measurable stress responses and even negative emotions in people. And all this without them being aware.
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The researchers also used a machine learning technique called ‘conditional inference forest’ to identify which factors best predicted whether infrasound had been present. The feeling of sadness, cortisol level measured after the trial and irritation lined up closely with the findings from conventional statistical analysis, giving the results additional credibility.
Why it matters
Infrasound is surprisingly common in modern cities. Ventilation systems, air conditioners, pipes, traffic and the mechanical systems running inside large buildings all produce infrasound on a constant basis. Wind turbines, which are becoming an increasingly important part of India’s renewable energy landscape, are another significant source.
For millions of Indians living in crowded cities or near industrial areas, infrasound may be a largely unnoticed part of the everyday environment. Researchers say more studies are needed to understand whether long-term exposure could influence mood, stress or overall wellbeing.
“Without auditory detection nor expectancy effects, infrasound exposure was linked to elevated cortisol and more negative affective self-reporting”, as mentioned in Frontiers in Behavioural Neuroscience, 2026.
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The most striking finding was not simply that infrasound affected people; it was how it affected them without their knowledge. When tested, participants were no better than random chance at identifying whether infrasound had been switched on. They had absolutely no conscious awareness of it. And later their bodies showed measurable biological responses.
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People exposed to infrasound rated the music they heard as sadder and less engaging, reported feeling more irritable during the session, and showed a statistically significant rise in cortisol levels measured through their saliva, a clear sign that their bodies were responding to something their minds could not even detect.
As the study published in Frontiers in Behavioural Neuroscience in 2026 concluded, these findings highlight the importance of identifying and reducing sources of infrasound pollution in the spaces where we live and work.
(The author Paramita Datta is an intern with The Indian Express)
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