Researchers at MacEwan University tested whether infrasound — sound below the range of human hearing — contributes to the eerie sensation people report in 'haunted' places. Volunteers listened to calming and horror-style music while hidden subwoofers introduced infrasound; participants reported more irritability, less interest, and perceived the music as sadder when infrasound was present. Saliva samples showed increased cortisol after exposure, and hormone elevations persisted afterwards. The authors warn that common urban sources of infrasound may be an overlooked form of noise pollution with mental health implications.
Infrasound May Make Places Feel 'Haunted' — Study Links Low-Frequency Noise to Irritability and Stress
These Weird Sounds Are Making Places Seem HauntedJordan Lye - Getty Images
Many people describe certain locations as having an undefinable, oppressive atmosphere: shutters that tremble, doors that creak, and shadows that seem to move on their own. New research suggests that at least some of that eerie feeling may come from infrasound — very low-frequency sound waves below the range of human hearing that can nonetheless affect mood and physiology.
What Is Infrasound?
Infrasound refers to sound waves with frequencies below the typical human hearing threshold. These subaudible vibrations are produced by natural events such as volcanoes, hurricanes and earthquakes, as well as by many human-made sources including traffic, plumbing, ventilation and HVAC systems, industrial equipment, and even the low-frequency energy that can accompany live music.
The Experiment
Psychologists Rodney Schmaltz and Kale Scatterty of MacEwan University in Edmonton tested whether infrasound can produce the sensations people often label as 'haunting.' Volunteers listened to short clips of ambient or horror-style music through computer speakers while infrasound was secretly introduced from hidden subwoofers. The music files were prefiltered so they did not contain infrasonic frequencies; any infrasound came only from the concealed sources. After each clip participants rated their emotions and provided saliva samples to measure cortisol, a hormone commonly used as a marker of physiological stress.
Key Findings
When infrasound was present, listeners reported greater irritability, lower interest, and a tendency to perceive the music as sadder compared with conditions without infrasound. These effects were observed for both calming and horror-style tracks, though responses were generally stronger for unsettling music. Saliva tests showed higher cortisol levels following infrasound exposure, and those elevations persisted after the exposure ended. Importantly, the study found more evidence for annoyance and irritability than for a direct link to clinical anxiety.
Implications
The results suggest that hidden physical sources such as rumbling pipes, groaning furnaces, or other low-frequency noise may contribute to the negative aura people associate with 'haunted' places. Beyond isolated spooky experiences, the authors raise a broader concern: because infrasound is common in urban environments, persistent exposure could constitute a form of noise pollution with implications for mental well-being. Identifying and mitigating chronic sources of infrasound may therefore be valuable for public health.
Infrasound is associated with negatively affective states. Considering the prevalence of infrasound in and around human habitats, these findings emphasize the potential value of identifying and mitigating sources of infrasound pollution within our environments.
Limitations: The study was conducted in a controlled setting and focused on short-term responses. While the findings support a role for infrasound in producing irritability and raised cortisol, further research is needed to determine long-term effects, underlying mechanisms, and real-world exposure thresholds.
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