Rock paintings offered more than just visuals for some prehistoric people. A new study by five Helsinki-based researchers examines the echoes produced by rock formations with paintings dating back between 5000 B.C.E. and 1500 B.C.E. throughout Finland’s Lakeland. After conducting acoustic tests amongst 37 such formations, they’ve deduced that Finland’s ancient hunter-gatherers joined the art and echoes into one multi-sensory, mystical experience.

Lead researcher Riitta Rainio told me over email that their work advances archaeology’s rising archaeoacoustics and New Materialism movements by focusing on reflected, not direct sounds. (Like echoes, as opposed to a bird chirping). “Reflected sounds have been overshadowed by direct sounds,” she wrote. “The new materialist perspective would seem to offer the possibility of seeing reflected sounds as important connections between humans and the environment.”

Rock art of a human holding a snake at Keltavuori. Photo: Julia Shpinitskaya.

“The study of prehistoric sonic cultures is largely based on material sources excavated from the ground, but these sources, mainly the remains of wooden, bone, or leather instruments, are often badly damaged,” the paper added. Meanwhile, rocks are apt to remain the same.

Rainio and her team studied 37 sites throughout Finland’s Lake District, which abounds with rock art depicting humans, boats, elk, snakes, and drummers. These waterways were popular, year-round routes for Bronze Age people. The sites consist of granite cliffs abutting water, sometimes angled towards it. Their faces are smooth, due to glacial grinding and a silica glaze naturally applied over time. At 26 of these sites, water levels have remained unchanged over millennia, meaning the acoustics are still the same, too. The team used 11 other sites as reference material, and made 83 field visits total.

Keltavuori rock art site in Finland during the summer. Photo: Julia Shpinitskaya.

People didn’t live amongst these cliffs. They were ceremonial spaces. During the winter, practitioners would walk out on ice towards the formations. During summer, they’d approach in canoes. As such, when the weather was warm, the researchers devised a system of anchoring their audio equipment to a custom raft, then riding out it in separate boats. Sometimes, winter conditions rendered their research dangerous.

The team played the sound of a bursting latex balloon from several spots surrounding these sites—from right up close to nearby dwelling areas—and recorded whatever bounced back. They also sang, chanted, and played instruments, and took laser scans to digitally recreate some of those experiences.

Across sites and seasons (but especially the unchanged formations, during summer) these rocks, polished into sonic mirrors by the elements, produced decisive slap echoes. What’s more, it seems people painted the spots that produced the most sound, which would have created the illusion of sentient artworks. But, it’s not conclusive whether Bronze Age folks did that on purpose. As the study notes, the best echoing facades also made for attractive canvases.

One thing is for sure. The echoes predate the art. And people definitely would have heard them.

Sound pressure level plots comparing impulse responses at Keltavuori rock art site (left) and a nearby dwelling site (right). Photo: Riitta Rainio.

Acousmatic sounds, or noises that have no visible source, are known to activate novel parts of the mind. The new study concludes by arguing that prehistoric people encountering these rocks may have experienced the real, recorded state of hallucinating their double. In this part of the world, that is the power of listening to a painting.