If you’ve ever visited a haunted house or a paranormal hotspot, you may have experienced a weird sense of unease that you couldn’t quite explain. While it’s tempting to imagine that these feelings signal the presence of ghosts or other supernatural entities, they may actually be caused by acoustic frequencies below 20 hertz, known as infrasound, according to a study published on Monday in Frontiers in Behavioral Neuroscience.
The human ear is not tuned to pick up infrasound, yet a growing body of research has shown that exposure to these frequencies nonetheless causes negative feelings in humans and many other animals. Now, scientists have probed this mysterious link with a new experimental approach involving 36 volunteers who self-reported their moods while listening to various musical styles that sometimes included infrasound.