The Hidden Effects of Infrasound on Stress and Irritation

That eerie sensation of being watched in an old house—or the prickly feeling that something is “off” in a dimly lit basement—may not be the work of restless spirits after all. A new study suggests that infrasound, a type of low-frequency noise below the threshold of human hearing, could be the real culprit behind many so-called paranormal experiences. The research, published in Frontiers in Behavioral Neuroscience, found that even brief exposure to infrasound can elevate stress levels and irritability, offering a scientific explanation for phenomena long attributed to ghosts or hauntings.

The Science Behind the Spooks

Infrasound refers to sound waves with frequencies below 20 Hertz (Hz), which are inaudible to the human ear. While some animals, such as elephants, use infrasound for long-distance communication, humans have no conscious awareness of these frequencies. However, the study reveals that our bodies still react to them. Researchers exposed participants to infrasound while playing music, monitoring their physiological and psychological responses. Though the subjects could not detect the infrasound, their salivary cortisol levels—a key indicator of stress—rose significantly. They also reported feeling more irritable during exposure.

Professor Rodney Schmaltz of MacEwan University, the study’s senior author, emphasized the ubiquity of infrasound in everyday environments. “Infrasound is pervasive in everyday environments, appearing near ventilation systems, traffic, and industrial machinery,” he said. “Many people are exposed 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.”

The implications of this research extend beyond the realm of ghost stories. Infrasound is commonly generated by aging infrastructure, such as old pipes, boilers, and ventilation systems—precisely the kinds of features found in many “haunted” locations. The study suggests that these inaudible vibrations could create a sense of unease or discomfort, which some individuals might interpret as supernatural activity. For skeptics, the same sensations might simply register as the creaks and groans of an old building. But for those predisposed to believe in the paranormal, the physiological effects of infrasound could provide fertile ground for ghostly explanations.

A Plausible Explanation for Paranormal Experiences

The idea that infrasound could influence human perception is not entirely new. Previous research has explored its potential effects on mood and cognition, though the mechanisms remain poorly understood. This study, however, provides concrete evidence linking infrasound exposure to measurable changes in stress and irritability. The findings align with anecdotal reports from paranormal investigators, who have long noted that “haunted” locations often coincide with sources of low-frequency noise, such as industrial equipment or faulty HVAC systems.

Schmaltz noted that infrasound alone is unlikely to convince someone that a place is haunted. Instead, it may contribute to a broader sense of unease that can be easily misinterpreted. “What infrasound may do is supply a bit of bodily discomfort that a ghost or haunting explanation can then attach itself to,” he explained. “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.”

Real-World Applications and Future Research

The study’s findings have practical implications beyond debunking ghost stories. Infrasound is a common byproduct of modern infrastructure, from highways and airports to factories and power plants. Understanding its effects on human health could inform urban planning, workplace safety regulations, and even architectural design. For example, buildings with poor sound insulation or aging mechanical systems might inadvertently expose occupants to harmful levels of infrasound, leading to chronic stress or irritability without an obvious cause.

Future research could explore the long-term effects of infrasound exposure, as well as potential mitigation strategies. For instance, sound-dampening materials or improved ventilation designs might reduce infrasound levels in older buildings, improving occupants’ well-being. The study opens the door to further investigation into how other inaudible environmental factors—such as electromagnetic fields or air quality—might influence human perception and behavior.

A Shift in How We Understand “Haunted” Spaces

For centuries, ghost stories have captivated human imagination, often serving as explanations for the unexplained. This study challenges that narrative by providing a scientific basis for many paranormal experiences. While it does not rule out the possibility of ghosts, it offers a more mundane—and testable—explanation for the sensations that have fueled ghost lore for generations. As Schmaltz put it, “The cause might be vibrating pipes rather than restless spirits.”

The research also underscores the importance of critical thinking when evaluating unusual experiences. What might feel like a supernatural encounter could, in fact, be the result of invisible environmental factors. By shedding light on the role of infrasound, this study bridges the gap between science and folklore, offering a new lens through which to view the mysteries of “haunted” spaces.

As technology advances, our understanding of the unseen forces that shape our perceptions will continue to evolve. For now, the next time you feel a chill in an old house, you might want to check the boiler—it could be the real ghost in the machine.