If you’ve ever felt stalked by something seemingly not-of-this-world, you’re far from alone. Research out today, however, might offer a mundane, if still profoundly creepy, explanation for some of these encounters with the supernatural. Scientists in Canada exposed volunteers to low frequencies of sound normally imperceptible to the human ear, also known as infrasound. Compared to control subjects, people exposed to infrasound reported feeling more irritable and experienced higher cortisol levels, a marker of stress, the researchers found. The study’s results suggest that hidden sources of infrasound can be a cause of the heebie-jeebies often linked to reportedly haunted places, the researchers say. “It is important to be clear that infrasound does not cause people to believe they have seen a ghost.…