‘Devil’s’ cave was thought to contain spirits — but ‘rare’ phenomenon was at play

The “Devil’s Church” — a famous cave in Finland — had long been thought by some to contain supernatural beings. The devil, though, was in the details, researchers said.

The narrow cave, located in a mountainside about 20 miles from the Russian border, was historically frequented by sages seeking to commune with the spirit world.

During rituals hosted in the cavern, sages often “shouted, raged, jumped, kicked, and trembled, as if fighting with or intimidating invisible forces,” according to a study published on Nov. 25 in the journal Open Archaeology.

Even today, the cave is visited by shamans, who conduct drumming sessions inside its winding tunnels.

The cave’s long-lasting appeal to religious practitioners piqued the interest of researchers from two universities in Finland, who set out to get to the bottom of its seemingly mythical properties.

In 2019 and 2020, the researchers set up audio recording instruments in the cave — which measures several feet wide and snakes about 110 feet into the mountain.

They then popped balloons throughout various points inside the stone-lined corridors in order to “obtain a comprehensive view of the acoustics.”

The recordings of the exploding balloons, as well as handclaps and voices, were then studied, revealing a “rare” and “distinct” resonance phenomenon.

The phenomenon, caused by noises made between flat, parallel walls, creates a tone emitted at a specific frequency that rings out, lingering in the air for about one second, according to a news release from the University of Eastern Finland.

This phenomenon is common in man-made structures like small rooms, but it is seldom found in the natural world, where smooth, parallel surfaces are abnormal, researchers said.

This noise amplification effect, though subtle, may have impacted religious experiences reported in the cave, providing the “means of deep connection and transaction with some kind of other-than-human participant or agent.”

“Where a researcher of acoustics hears as resonance, people of the past may have sensed the presence of a spirit, and a shamanic practitioner may feel the presence of an exceptional energy,” researchers said.

The study demonstrates how religious belief can impact sensory perceptions, resulting in distinct experiences and different explanations.

This story was originally published November 28, 2023 at 5:36 PM with the headline "‘Devil’s’ cave was thought to contain spirits — but ‘rare’ phenomenon was at play."