Scientists Say They Have Finally Figured Out What Causes Ghosts

Thirty-six people sat alone in a room listening to music. Half of them walked out irritable, mildly anxious, and convinced the music felt sadder than it was. The other half walked out fine. The only difference between the two groups was something none of them could hear.

That experiment, published in April 2026, didn’t set out to study music perception or mood. The researchers were after something more specific: a plausible physical explanation for what causes ghosts. Or more precisely, what causes people to feel like they’re in the presence of one. The answer they found was already in the walls.

Old buildings have long held a reputation for being unsettling, especially basements, boiler rooms, and long institutional corridors. For decades, people assumed that was psychology doing its work – suggestion, darkness, creaking wood. The 2026 study suggests the explanation is more physical than that, and stranger. A frequency of sound you cannot consciously hear may be making your body respond to a threat that isn’t there.

What Causes Ghosts, According to the New Research

Rodney Schmaltz, a psychologist at MacEwan University in Canada and co-author of a new study published in Frontiers in Behavioral Neuroscience, told The Guardian: “What infrasound may do is supply a bit of bodily discomfort that a ghost or haunting explanation can then attach itself to.” The implication is precise. Infrasound doesn’t put a ghost in your mind. It creates a physical feeling of unease that, for certain people, needs an explanation – and a haunting is the one their brain reaches for.

Schmaltz elaborated: “For someone who is not inclined to think in terms of ghosts, the same sensation would probably just register as a stuffy, uncomfortable old building. For someone who is already primed, it might feel like proof of a spirit or presence.” The same invisible vibration, two completely different interpretations – determined not by the sound, but by the person receiving it.

Chris French, a psychologist emeritus at Goldsmiths, the University of London, who studies paranormal beliefs and was not involved in the research, said it’s “plausible” that feelings caused by low-frequency sound might lead some people to feel a place is “haunted” – though that could be all there is to it. French’s caution is worth keeping: infrasound may be a partial explanation, not a total one.

What Infrasound Actually Is

Infrasound sits below roughly 20 Hz, the lower limit of what the human ear can ordinarily detect. It’s generated by storms, volcanic activity, tectonic rumblings, and the mechanical infrastructure of cities: aging pipes, HVAC systems, traffic, industrial machinery. It’s not exotic. It’s everywhere.

While humans cannot hear infrasound, they can feel it. The body picks up these vibrations even when the auditory system doesn’t register them as sound. This distinction matters – you can’t tune it out, you can’t consciously notice it, and you certainly can’t trace your discomfort back to it without specialized equipment.

As Schmaltz himself noted, “infrasound produces real, measurable reactions without any visible or audible source.” That combination – a real physical effect with no identifiable cause – is precisely the kind of experience that gets labeled paranormal.

The Experiment That Measured the Effect

To conduct a tightly controlled experiment, Schmaltz and his colleagues recruited 36 participants, three-fourths of whom were women. Even though participants couldn’t hear the infrasound, those exposed to it were put into an uneasy state of mind and showed a measurable stress response, according to the study in Frontiers in Behavioral Neuroscience.

Researchers found that infrasound – low-frequency vibrations common in everyday environments – can increase irritability and stress hormone levels without people realizing it’s there. The stress hormone in question was cortisol, measured directly from saliva samples taken during the session. Cortisol concentrations rose significantly in those exposed to infrasound, providing a biological marker that went beyond self-reported mood.

As Schmaltz explained: “None of this depended on whether people thought the infrasound was on. When we asked participants at the end of the session whether they believed they had been exposed, their answers were no better than guessing, and their beliefs did not predict their mood or cortisol responses.” The effects, he concluded, were not driven by people consciously noticing the stimulus and reacting to it. That rules out a simple placebo effect – the body was responding to something real.

The Mood Changes Were Specific and Measurable

The physiological response was only part of the picture. Compared to control subjects, people exposed to infrasound reported feeling more irritable and experienced higher cortisol levels. They also rated the music they were listening to as sadder, regardless of whether it was calming or unsettling in nature.

Schmaltz noted that “many people are exposed to it without knowing it,” and 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.” The mood changes weren’t dramatic enough to be obvious – participants didn’t feel suddenly terrified. They just felt worse, in a low-grade, sourceless way.

Consider visiting a supposedly haunted building. Your mood shifts, you feel agitated, but you can’t see or hear anything unusual. The absence of an obvious explanation is what leaves the door open for supernatural interpretation – especially in someone who already leans toward believing.

Where Infrasound Hides in Everyday Spaces

Infrasound is pervasive in everyday environments, appearing near ventilation systems, traffic, and industrial machinery, according to Schmaltz. Old buildings concentrate these sources. Basements full of aging pipes, boiler rooms with industrial-era machinery, long underground corridors near subway lines – these aren’t spooky by accident.

The MacEwan study was led by Kale R. Scatterty, Trevor J. Hamilton, and Rodney M. Schmaltz, along with co-authors Dawson VonStein, Lisa B. Prichard, and Brian C. Franczak, and part of their reasoning for the study was the inconsistency in earlier infrasound research. Some prior studies found infrasound linked to fatigue, nausea, and anxiety; others reported no significant effects. The inconsistencies were largely attributed to weak experimental controls, unverified sound exposures, and over-reliance on self-report.

The 2026 study addressed that gap by using a verified infrasonic frequency (18 Hz) and pairing it with both psychological self-report and a biological marker. Lead researcher Kale Scatterty noted: “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.” If different frequencies produce different effects, the spectrum of “haunted” sensations may be wider than this single study captures.

How Common Ghost Belief Actually Is

The cultural backdrop here matters. A 2025 Gallup poll found that 39% of Americans express a belief in ghosts, conducted across 1,003 American adults between May 1 and 18, 2025. A separate YouGov poll found that 60% of Americans believe they’ve experienced at least one paranormal event in their lives, with the most common kind – at 35% – being “feeling a presence or unknown energy.”

That last finding is the one that connects most directly to the infrasound research. Feeling an invisible presence, with no visual or auditory cause, is exactly the kind of experience that low-frequency vibrations could generate. The person doesn’t see anything. They don’t hear anything. They simply feel something is there.

As French noted to The Guardian, it “may be a step too far to explain alleged poltergeist activity, such as objects flying off shelves, as resulting from infrasound.” The research makes no sweeping claim. It identifies one plausible physiological pathway to one specific type of paranormal experience – the vague, atmospheric sense that something is wrong in a room.

What the Research Doesn’t Explain

The 2026 study is a controlled starting point, not a comprehensive theory. The researchers acknowledge that the study’s sample size is small, though the findings did hold up under different sensitivity analyses used to gauge how robust the results are likely to be. Thirty-six participants is a thin base for broad conclusions.

Schmaltz told Nautilus that future work should examine longer-term exposures to infrasound. The current experiment used a brief, single-session exposure at one specific frequency (18 Hz). Real-world environments like old buildings generate infrasound continuously, across multiple frequencies, sometimes for hours or days. Whether longer exposure produces stronger effects, stranger ones, or no additional effect at all is still unknown.

The study also doesn’t address visual ghost experiences. People who report seeing apparitions, figures, or shadows are describing something that infrasound alone can’t easily explain. Some research has suggested that infrasound vibrations in the eyeballs can lead to visual disturbances, including seeing shadows or flickering lights that might be mistaken for ghostly apparitions – but that remains a separate, less-established line of inquiry from the controlled cortisol and mood research published in 2026.

What This Means for You

Many people are exposed to infrasound without knowing it, and even brief exposure may shift mood and raise cortisol – the stress hormone your adrenal glands release in response to perceived threats. If you’ve ever walked into a basement, an old office, or an unfamiliar building and felt inexplicably uneasy, tense, or irritable without any obvious cause, infrasound is a legitimate candidate. Your body genuinely responded to something real. You just couldn’t hear it.

If the patterns from this research hold across further testing, the findings could eventually inform noise regulations or building design standards. For now, if you work or live in a building with aging HVAC systems, old boilers, or heavy nearby traffic – and you notice persistent low-grade irritability, mild anxiety, or a nameless sense of discomfort – it’s worth asking a building engineer whether the mechanical infrastructure has been assessed for low-frequency noise output. The feeling might have nothing to do with the building’s history, and everything to do with what’s vibrating inside its walls.

Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.

AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.

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