Death whistles are ancient Aztec artifacts that produce frightening sounds reminiscent of the piercing screams of 1,000 dead people. These skull-shaped objects have long fascinated archaeologists and historians, and a groundbreaking study by scientists at the University of Zurich reveals for the first time the complex psychoacoustic role of the death whistle. This extensive research shows that these strange devices can trigger profoundly disturbing effects on the human brain.
The Death Whistle: A Scary Object of Undeniable Historical Importance
Discovered in the 19th century, the death whistle is believed to come from the Postclassic Mesoamerican period which covers the years 1250 to 1521. These small clay instruments shaped in the shape of a skull and measuring three to five centimeters have a remarkably complex internal structure which makes it possible to ingeniously channel the flow of air emitted by the mouth to produce a high-pitched, bone-chilling sound which is reminiscent of a human cry.
« Whistles have a very unique construction, and we know of no comparable musical instruments from other pre-Columbian cultures or other historical and contemporary contexts “, says Dr Sascha Frühholz, lead author of the study and professor of cognitive and affective neuroscience at the University of Zurich
Its particular shape has led researchers to associate it with Mictlantecuhtli, the Aztec lord of the underworld. Others, however, suggest that its howling, wind-like tones could symbolize Ehecatl, the Aztec god of wind who ventured into the underworld to recover the bones of a previous age and create humanity according to Mesoamerican mythology.
The intense psychoaffective effects of the death whistle
Although this instrument has captured the popular imagination, notably with a notable appearance in the filmGhostbusters: Legacyin 2021, few scientists are interested in its exact function and importance in Aztec society. To better understand the physical mechanisms related to this mysterious sound tool and its impact on listeners, researchers from the University of Zurich, led by Dr. Frühholz, conducted one of the most in-depth studies to date on this object.
To do this, the team used computed tomography (CT) scanners and 3D modeling to reconstruct original Aztec death whistles housed at the Ethnological Museum in Berlin. By playing these reconstructions under different air pressures, the researchers generated over 270 audio recordings to reveal the key acoustic characteristics of the instrument with its sound described as piercing, and therefore very effective in capturing attention while arousing fear. Spectral analysis revealed harsh, turbulent sounds reminiscent of biological distress calls, high-pitched elements that mimic the shrill quality of a scream, and sudden, irregular bursts of sound that enhance their startling effect.
A test on human listeners
After dissecting the acoustic properties of the death whistle, researchers studied its psychological effects on listeners by recruiting 70 European volunteers. exposed to a random selection of sounds including tones produced by these whistles, but also human and animal noises, nature sounds (rain, wind, etc.), musical sounds and tool sounds. Volunteers were not informed beforehand that skull-shaped whistle sounds would be included.
Participants then systematically described the sounds of death whistles as “disgusting», «scary» et « unnatural” with “ cri » as the most frequently assigned label. The sounds evoked intensely negative emotionsincluding fear and discomfort, and listeners felt a strong sense of urgency, similar to the response triggered by an alarm. The study further highlighted that the neuronal responses here were similar to those elicited by aversive stimuli, such as human screams, highlighting the ability of the whistle to arouse fear and urgency.
Thirty-two of the participants also underwent fMRI (functional magnetic resonance imaging) brain scans while they listened to this sound mix. This made it possible to observe that the whistle activated more particularly the inferior frontal cortex and the medial frontal cortex, brain regions associated with auditory processingbut also to the interpretation of emotional and symbolic meaning.
A questioning of the role of these instruments
This study did not aim to determine the exact role of the aversive sound of death whistles in Mesoamerican culture. A popular theory, however, suggests that these archaeological curiosities served aspsychological warfare tools creating a deafening cacophony in battle to sow fear and confusion among enemy forces and provide a tactical advantage to the Aztecs.
However, the researchers believe that the strong association between whistle sounds and high-level cognitive processing suggests that use during the war is “rather improbable ». Instead, the study's evidence points to a ceremonial role reinforced by the fact that the whistles were mainly discovered in ritual burial sites associated with human sacrifices, notably in temples like that of Ehecatl-Quetzalcoatl in Mexico.
The universal effect of the death whistle
« The skull-shaped whistles may have been used to frighten the human sacrifice victim or ceremonial audiencebut further research is needed on this point», Estimate the researchers. And although it is obviously impossible to conduct psychological or neurological experiments on individuals from the Aztec era, this type of modern study shows that basic affective responses to terrifying sounds are universal in humans and that the reactions at the time would have been similar to those we experience today.
This interdisciplinary research which makes a fascinating link between archaeology, neuroscience and acoustics offers in any case valuable insights into the way in which sound influences human cognition and emotionsand could inspire new studies looking at how ancient cultures exploited sensory experiences.
In the video below you can hear an example of a reconstructed Aztec death whistle. We recommend lowering your volume if you are wearing headphones to experience these sound clips comfortably.
Published on November 11, 2024 in Communications Psychology, the study can be found here.
