If you were to ever have the displeasure of going to war against the Aztecs, the Mesoamerican people who dominated much of central Mexico in the 14th century, your ears would be greeted by ghoulish screams and shrieks long before you saw any of their warriors. The screaming cacophony of noise, rivaled only by a barbershop quartet led by banshees, would fill the soundscape of the woodland battlefields and invoke fear into their enemies. And this symphonic horror was all thanks to a small whistle that could fit in the palm of your hand.

The Aztec Death Whistle, as it’s called today, was used as a means of psychological warfare to startle enemy tribes. The Aztecs also used death whistles for ceremonies such the Day of the Dead.

Now researchers are trying to piece together new death whistles from fabricated parts in hopes of recreating how they sounded in the past and what their effects are on the human brain.