Ancient Aztec death whistle still terrifies people today, study finds — and you can listen if you’re brave enough

Its fear-splitting screech reverberates throughout space and time.

Swiss and Norwegian neuroscientists have discovered that the ancient Aztec death whistle — often credited with emitting the scariest sound on earth — still terrifies people today due to a primal fear response. They revealed their spine-tingling finding in the journal Communications Psychology where it’s currently scaring up interest online.

“We show that skull whistle sounds are predominantly perceived as aversive and scary and as having a hybrid natural-artificial origin,” wrote the researchers, who hail from the University Of Zurich.

These small, skull-shaped whistles were exhumed from gravesites dating back to between 1250 and 1521 AD, leading researchers to believe that they were related to the afterlife.

When archaeologists blew into these creepy kazoos, they emitted an unearthly, banshee-like shriek similar to a haunted house’s sound effect.

The Aztecs modeled the death whistle after the human larynx, so that when blown into, the wind splits in two, producing oscillating sound waves that bounce around a large chamber before exiting via a second hole — like the velociraptor voice box from “Jurassic Park”

To test if this instrument of terror still resonated today, the researchers asked 70 European volunteers to interpret various sounds, including the scare-horn’s trademark scream.

Participants didn’t know beforehand that the whistle would be included, removing any preconceptions of it ahead of the experiment, Science Alert reported.

During the test, researchers asked volunteers to describe the sensation while simultaneously monitoring some of them with a device that measured their neural and psychological responses to the death whistle.

Scientists found that the sound activated certain low-level auditory regions of the brain, suggesting that they were on edge.

Meanwhile, the volunteers claimed that the sound made them feel scared and aversive to the point that they wanted it to stop.

Researchers chalked up this effect to the fact that the death whistle’s screech blurs the line between the natural and the artificial, like the uncanny valley effect for sounds.

They specifically categorized it alongside alarm sounds such as sirens as well as human-adjacent noises of fear, anger, pain and sadness. These trigger the aforementioned auditory response in humans and spur us to analyze the unsettling noises on a deeper level.

“Skull whistle sounds are… rather ambiguous in the determination of their sound origin, which intensifies higher-order brain processing,” the researchers wrote.

In other words, death whistles are petrifying on a primal level that goes beyond some run-of-the-mill loud noise.

Despite their terrifying nature, these fright flutes weren’t necessarily designed solely to scare — although researchers did theorize that was definitely one of their functions.

Their prevalence in gravesites led researchers to suspect that these petrifying piccolos may have been symbols of Ehecatl, the Aztec God of Wind who “traveled to the underworld to obtain the bones of previous world ages to create humankind.”

“Given both the aversive/scary and associative/symbolic sound nature as well as currently known excavation locations at ritual burial sites with human sacrifices, usage in ritual contexts seems very likely, especially in sacrificial rites and ceremonies related to the dead,” researchers concluded.

Some had previously postulated that the scream machines were defense talismans used to ward off evil spirits during a sacrificial victim’s journey to the afterlife.