Infrasound—low-frequency noise below 20 Hz—could explain eerie feelings in allegedly haunted locations, according to a study published in *Frontiers in Behavioral Neuroscience*. Researchers found exposure to infrasound increased cortisol levels, a stress hormone, and heightened irritability in participants, even when they couldn’t consciously detect the sound. The experiment involved 36 people in a lab setting, where hidden subwoofers emitted infrasound during ambient music. Cortisol spikes were consistent across all participants, suggesting a universal physiological response to these invisible vibrations.

Earlier research by psychologist Richard Wiseman linked hauntings to environmental factors like magnetic fields and humidity. In 2003, Wiseman’s studies at Hampton Court Palace and Edinburgh’s South Bridge Vaults showed people reported paranormal sensations in areas with abnormal lighting or magnetic variances. Similarly, the late engineer Vic Tandy theorized infrasound from machinery caused visual distortions, such as phantom figures, in a lab and cathedral. However, the new study found no evidence of visual illusions, focusing instead on auditory stress responses.

While the results are compelling, the study’s small sample size and limited funding—reportedly $8,000—highlight its preliminary nature. Co-author Rodney Schmaltz emphasized that infrasound is likely one piece of a larger puzzle, alongside suggestibility and expectation. His team plans to measure infrasound levels in real haunted sites but admits current readings show “not much difference” between reputed haunted and non-haunted spaces. The work underscores the need for larger, diverse studies to disentangle fact from folklore in paranormal investigations.

Key takeaway: Infrasound may amplify unease in old buildings, but it’s not the sole cause of hauntings. As Schmaltz notes, “We’re not claiming to solve hauntings,” but understanding these triggers could reshape how we approach ghost stories—and the science behind them.