Experiment playing 17.5 Hz sound makes listeners scared

In 2003, scientists conducted a strange experiment with 750 volunteers in the form of a concert that caused fear and anxiety.

It has long been suspected that infrasound – low-frequency sounds beyond the human hearing range – can have strange effects on listeners. But in 2003, there was little research on the subject. So a team of scientists from the UK's National Physical Laboratory decided to try playing infrasound at a concert alongside regular music.

The pipe organ is said to produce infrasound that makes listeners shiver. (Photo: Nina Alizada).

"In our experiment, we wanted to determine whether infrasound in music can produce unusual psychological effects, even when listeners are not aware of its presence," explains Sarah Angliss, a composer and sound designer involved in the project.

"Of particular interest are the emotional effects. Infrasound is used in 'sacred' music , for example in organ performances in cathedrals. The reason for its use is a matter of debate. Some argue that the sound adds a sense of awe, making listeners shiver. Others argue that the giant pipes emitting infrasound are just 'an expensive way to create a breeze'. Strangely enough, infrasound has also been found in some places that are considered haunted, creating a sense of unease in listeners," she added .

In one example Angliss cites, scientists working at a lab in Coventry, England, reported feelings of unease, shivers, and other strange phenomena, including seeing 'shapes' in the corner of one scientist's vision. When one scientist noticed the metal foil in a clamp vibrating violently, he investigated and found what might be the cause of all the trouble: The lab's new exhaust fan was generating infrasound. When the fan was turned off, the trouble went away.

Back in 2003, a team from the UK's National Physical Laboratory decided to play sounds at 17.5 Hz, beyond the range of human hearing, through a 7-meter-long tube during a concert in London. The infrasound was only played during certain songs, and the audience was not told which ones. Despite this, 22% of the 750 people in the audience reported feeling strange effects during the infrasound music. These effects included sadness, shivers, uneasiness, and fear.

"These results suggest that infrasound can cause people to have strange experiences even when they are not aware of the low-frequency sounds. Some scientists have suggested that this sound may be present in some supposedly haunted places and cause strange feelings that people attribute to ghosts - our findings support this idea ," said Professor Richard Wiseman, a psychologist at the University of Hertfordshire.

Later studies, including a study of deliberately set-up 'haunted rooms' in the journal Cortex in 2009, have also shown that infrasound can produce effects similar to those of hauntings in humans. Of course, not all hauntings can be explained this way. Other explanations include hoaxes, carbon monoxide poisoning, and phenomena that are not yet fully understood.