It seems scientists have found another explanation for haunted houses
Sometimes you walk into an old building, and something immediately feels off. Nothing seems to be happening, but a sense of anxiety and discomfort won’t let go. If you explored abandoned buildings as a child, you know this feeling well. New research has shown that the cause may be infrasound — sound waves so low that the human ear can’t hear them. But the body reacts: stress hormone levels rise, mood worsens, and the person doesn’t even understand what exactly is bothering them.
What Is Infrasound
Infrasound consists of sound waves with a frequency below 20 hertz, meaning below the threshold of audibility for most people. It can occur naturally from tectonic or volcanic activity, storms, and the interaction of air with water. But nature isn’t the only source of these waves. Infrasound is also common in urban environments, near ventilation systems, air conditioners, pipes with low-frequency hum, automobile traffic, and mechanical building systems.
Imagine a huge invisible drum that beats so slowly that your ear can’t catch the rhythm. But the pressure waves still pass through walls and through the body. That’s exactly how infrasound works: you hear nothing, but your body senses the pressure fluctuations and reacts to them.
Old heating systems, boilers, ventilation, and plumbing pipes — all of these are potential infrasound generators. And it’s precisely in old buildings, where equipment hasn’t been updated in a long time, that such sources are especially common.
Infrasound Raises Stress Hormones
A group of Canadian scientists decided to test whether infrasound affects people even when they don’t notice it. The researchers recruited 36 volunteers, mostly young women with an average age of about 23. Each participant was randomly assigned to one of four groups: calm music with infrasound, calm music without infrasound, anxious music with infrasound, or anxious music without infrasound.
For half the participants, hidden subwoofers produced infrasound at a frequency of 18 Hz. The infrasound exposure lasted just under five minutes. Saliva was collected before the session began and 20 minutes after — this window was chosen to capture changes in cortisol levels.
The results were published in the journal Frontiers in Behavioral Neuroscience in April 2026.
Irritation, Sadness, and Stress from Infrasound
When infrasound was on, participants reported increased irritability. They found the music less interesting. They rated it as sadder. Salivary cortisol levels, a hormone often used as a stress marker, also rose after exposure.
No increase in anxiety was detected, although it was previously assumed that infrasound could cause it. The effect wasn’t like anxiety or panic — rather, it was a subtle shift toward stress, irritability, and negative mood. A feeling of “something is wrong” that can make a room unpleasant, even though no one understands why.
What’s especially interesting is this: according to Professor Rodney Schmaltz, the body can react to infrasound even if we don’t consciously hear it. Participants couldn’t determine whether infrasound was on, and their guesses about it had no effect on cortisol levels or mood. In other words, the effect didn’t depend on expectations or suggestion — the body reacted on its own.
Why Ghosts Are “Seen” in Old Houses
The sensations caused by infrasound match what people often describe in “haunted houses.” This idea is supported by the fact that old houses are very likely to produce infrasound themselves.
Professor Schmaltz, who studies pseudoscientific and paranormal beliefs, describes the mechanism as follows: infrasound creates mild physical discomfort, and then the person finds their own explanation. This is especially noticeable in basements, where old pipes and ventilation create low-frequency vibrations. If someone is told in advance that a building is haunted, they may attribute the irritation to something supernatural.
This idea isn’t new. Back in 1998, British engineer Vic Tandy, working in a medical equipment laboratory, felt an oppressive atmosphere, cold shivers, and saw an indistinct gray figure. Investigating the cause, he discovered that a recently installed fan was creating a standing infrasound wave at a frequency of 19 Hz. The frequency turned out to be close to the resonant frequency of the human eyeball — the waves made the eyes vibrate and caused an optical illusion.
The new study adds an important detail to this picture: there is now a biological marker of the response to infrasound — elevated cortisol. This is an objective indicator, independent of subjective feelings.
Criticism of the Study
The sample size was relatively small, so the scientists conducted a sensitivity analysis before drawing conclusions. They confirmed that their study could detect medium and large effects of infrasound. However, to fully understand how infrasound affects emotions and behavior, larger and more diverse studies are needed.
This study was largely a first step toward understanding the effects of infrasound on humans. So far, only one frequency has been tested. Other frequencies and their combinations may produce different effects.
There are other limitations as well. The study did not test infrasound directly in “haunted houses” or near boilers. In the laboratory, a pure tone from a subwoofer was used, while real infrasound in buildings is a complex mix of frequencies and vibrations. Chris French, an emeritus professor of psychology who was not involved in the work, notes that research results on infrasound have been mixed so far. According to him, it’s plausible that sensations from low-frequency noise can make people think a place is “haunted,” but explaining phenomena like objects flying off shelves with infrasound would be a stretch.
An old building’s plumbing system — a potential source of invisible stress
Should You Check Your Home for Infrasound
Even if the connection to “ghosts” remains a hypothesis, the practical aspect of the research is quite concrete. According to Professor Schmaltz, infrasound is everywhere — near ventilation systems, transportation, and industrial equipment. Many people are exposed to it without even knowing. Research results show that even brief exposure can alter mood and raise cortisol.
Professor Trevor Hamilton adds that a short-term rise in cortisol is a normal stress response that helps the body mobilize. But chronic elevated cortisol is a problem: it can lead to various physiological disorders and affect mental health. This means that constant exposure to infrasound in residential or work spaces is an issue that deserves serious attention.
Special instruments for measuring infrasound exist, but they aren’t part of standard inspections for apartments or offices. Nevertheless, if a space consistently produces an unexplainable sense of discomfort, it’s worth paying attention to the condition of the ventilation, heating, and other mechanical systems.
The study doesn’t put a final answer on the question of haunted houses — but it offers a testable scientific explanation for sensations that were previously attributed to mysticism or imagination. And perhaps next time something feels off in a basement or an old building, it’s worth thinking about vibrating pipes rather than restless spirits.
