While excavating an ancient temple within the ruins of the Aztec city-state of Tlatelolco in 1999, archaeologists discovered a 500-year-old skeleton buried with two mysterious objects in his hands: clay whistles resembling skulls. The significance of these instruments was unknown, but one thing was certain, the sounds they produced were chilling.

One scholar associated with the Mexico City dig described the noise to Gizmodo as “a shriek of death”, in an interview for their Sound Mysteries series.

Other examples of these “death whistles” have been found at several other ancient Mesoamerican sites associated with the Aztec culture, with the first official description in 1971 by historian José Luis Franco. But, according to Roberto Velázquez Cabrera, a mechanical engineer who specializes in the history and reconstruction of such instruments, none had ever been unearthed alongside other objects, let alone human remains, that could help clarify the whistle’s purpose through context.

So, for many decades, these objects were treated as mere curiosities, packed off to languish in museum storage based on the assumption that they were long ago-discarded toys rather than important spiritual relics. 

Yet the Tlatelolco find changed all that and kicked off a whirlwind of research that continues to this day. Examinations of the skeleton revealed that the individual was a 20-year-old man who had been beheaded as a sacrifice. He had been buried in front of a temple dedicated to the wind and rain god Ehecatl.

Given this new information, anthropologists speculated that the sibilant wind instruments could have been used to mimic howling air in honor of the deity, and/or help guide the sacrificial victim to the afterlife, honor the god of death Mictlantecutli, and/or for use in battle to stir the troops and scare enemies.

As you can tell, there is still some uncertainty.  

However, thanks to researchers like Cabrera, a musician named Xavier Quijas Yxayotl, and music archaeologist Arnd Adje Both, we now know how the whistles’ disturbing sounds are created. Studies of the whistles and experiments using carefully made replicas have shown that the two-chambered instruments form multiple air streams that then clash together to dramatic result.

After Yxayotl helped introduce the general public to the death whistle by using it in his performances and supplying Mel Gibson with one for use in the film Apocalypto, death whistles have moved from overlooked artifacts to popular items, according to Culture Trip. Cheap recreations are hawked outside many Aztec tourism sites, more artistic versions can be found on Etsy, and Yxayotl sells handmade ones on his website, which states that each skull whistle recreates the "scream of a thousand corpses".

[H/T: Gizmodo and Culture Trip]