- Infrasound is low-frequency sound below the range of human hearing. This sound can come from sources such as storms, traffic or even vibrating pipes in buildings.
- Recent experiments showed people can’t hear infrasound, yet their bodies still react to it. They showed higher stress hormones and increased irritability after exposure to infrasound.
- This reaction could explain some paranormal experiences. The unease or discomfort in old, abandoned buildings could stem from infrasound due to vibrating pipes, for example.
Frontiers published this original story on April 27, 2026. Edits by EarthSky.
Could paranormal experiences be due to low-frequency sound?
Humans can’t hear very low-frequency sound, known as infrasound … But our bodies still seem to respond to it. That’s the finding of a new study published on April 27, 2026, in which researchers played infrasound for test participants alongside music.
They found that although the listeners couldn’t accurately detect the infrasound, their irritability and cortisol levels rose. Cortisol is the “stress hormone,” and high levels indicate anxiety. So this stress response suggests our bodies may react to infrasound even when we can’t consciously hear it. That invisible reaction might even help explain why people report unusual experiences in places like supposedly haunted buildings.
Infrasound and paranormal experiences
Infrasound is very low-frequency sound, below 20 Hertz (Hz), which humans typically can’t hear. It can come from natural sources like storms, or from human-made sources like traffic. Some animals use it to communicate, while others avoid it.
Scientists investigating humans’ ability to sense infrasound determined that we can’t detect it, but we do respond to it. They found it’s linked to increased irritability and higher cortisol levels.
Rodney Schmaltz of MacEwan University in Canada is the senior author of the new article in the peer-reviewed journal Frontiers in Behavioral Neuroscience. Schmaltz said:
Infrasound is pervasive in everyday environments, appearing near ventilation systems, traffic and industrial machinery. Many people have exposure to it without knowing it. Our findings suggest that even a brief exposure may shift mood and raise cortisol, which highlights the importance of understanding how infrasound affects people in real-world settings.
Consider visiting a supposedly haunted building. Your mood shifts, you feel agitated, but you can’t see or hear anything unusual. 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. If you were told the building was haunted, you might attribute that agitation to something supernatural. In reality, you may simply have been exposed to infrasound.
Registering a stress response
The scientists recruited 36 participants and invited them to sit alone in a room while they played either calming or unsettling music. For half the participants, hidden subwoofer speakers played infrasound at 18 Hz. After listening, the subjects reported their feelings, their emotional rating of the music and whether they thought the infrasound was present. They also gave saliva samples before and after listening.
The scientists found that participants’ salivary cortisol levels were higher if they had been listening to infrasound. These participants also reported feeling more irritable and less interested. And they reported thinking the music was sadder. But they couldn’t tell they were listening to infrasound. Schmaltz said:
This study suggests that the body can respond to infrasound even when we can’t consciously hear it. 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.
Kale Scatterty is the first author of the new study and a Ph.D. student at the University of Alberta. Scatterty said:
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. But infrasound exposure had effects on both outcomes that went beyond that natural relationship.
Sounds you don’t hear but your body notices
These results indicate humans can sense but not identify infrasound, though the mechanism remains unclear. They also suggest we may need to investigate whether prolonged infrasound exposure could impact health through consistently elevated cortisol levels and wellbeing issues related to lowered mood and increased irritability.
Trevor Hamilton of MacEwan University, corresponding author, said:
Increased cortisol levels help the body respond to immediate stressors by inducing a state of vigilance. This is an evolutionarily adapted response that helps us in many situations. However, prolonged cortisol release is not a good thing. It can lead to a variety of physiological conditions and alter mental health.
Larger studies come next
Because the sample was comparatively small, the scientists carried out sensitivity analyses before drawing conclusions from their results. They confirmed their study could detect moderate to large effects of infrasound, which includes their main findings. However, more research with greater, more diverse participant samples will be needed to fully understand how infrasound influences human emotion and behavior.
Scatterty said:
This study was in many ways a first step towards understanding the effects of infrasound on humans. So far, we’ve only tested a specific frequency. There could be many more frequencies and combinations that have their own differential effects. We also only collected subjective reports of how the participants felt after exposure, without directly observing their responses during the trial.
Schmaltz added:
The first priority would be testing a wider range of frequencies and exposure durations. 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. If those patterns become clearer, the findings could eventually inform noise regulations or building design standards. 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. 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.
Bottom line: Research shows people can’t hear sounds at very low frequencies, yet they still respond to them. Could these sounds explain paranormal experiences?
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