On the campus of Coventry University in England, there's a 14th-century cellar home to a ghost, or so people thought. Those who visited the cellar said that they had paranormal experiences, with some reporting seeing the ghost of a woman. Even a self-proclaimed witch became so spooked she quickly left after a few moments alone in the cellar.

The Fear Frequency

This story was debunked when Vic Tandy, a lecturer at the school and part-time ghost hunter, discovered what was later called "the fear frequency." By measuring infrasound levels, specifically at 18.9 Hz he determined that low frequencies can cause people to see optical illusions, get chills, feel anxious, and experience other paranormal-like effects. In other words, it can make you convinced you've seen a ghost, even if you haven't. And it turns out, the levels in that Coventry University cellar fall into a range where those effects are to be expected.