The wail of the Aztec Death Whistle was the last thing many human sacrifices ever heard before they met their untimely end.
The chilling noise is described as the ‘scariest sound in the world’, and is somewhere between a spooky gust of whistling wind and ‘the scream of a thousand corpses’.
Now, a study has found that this instrument is just as terrifying for people today as it was 500 years ago.
Scientists from the University of Zurich played the sound of the Aztec Death Whistle to a group of volunteers and recorded how their brains responded.
Participants who heard it reported feeling frightened, while the brain scans showed that the sound puts the listener on high alert, activating neural regions associated with core emotions like rage, fear, and grief.
Researchers believe the whistles could have been used to frighten victims and onlookers during human sacrifice rituals.
Lead author Professor Sascha Frühholz told MailOnline: ‘The sound is rough and high-pitched, and as listeners, you usually do not like such sounds.’
So, are you brave enough to listen to it?
Aztec Death Whistles are clay instruments typically shaped like skulls which have been found in grave sites of ritual sacrifice victims dated from 1250 to 1521 AD
Aztec Death Whistles, or Skull Whistles, are a type of unusual musical instrument found in grave sites dating from 1250 to 1521 AD.
Their unusual skull-like shape baffled archaeologists for years until one plucky researcher decided to blow into the opening at the top of one artefact.
When played with force, the resulting sound was a cacophonous, piercing wail reminiscent of human screams.
Archaeologists aren’t yet sure what these unusual instruments were used for but some suggest they could have either been used to terrify the enemy during battle or as part of human sacrifice rituals.
To learn more, the researchers decided to test how modern listeners who weren’t familiar with the Aztec Death Whistle would respond to the sound.
Professor Frühholz said: ‘Since the Aztec skull whistle sounds close to a human scream, we wanted to investigate if humans have the same negative and aversive response to Aztec death whistle sounds.’
A group of European participants were played recordings of genuine Aztec Death Whistles, replicas, and whistles of the researcher’s own creation alongside a set of other recorded sounds.
The participants were then asked to describe what they heard and how it made them feel while their brain activation was recorded by functional magnetic resonance imaging (fMRI).
Almost universally, the sound produced a strong negative emotional response as well as a sense of urgency and arousal.
In terms of the effect on the listener, the Death Whistle was found to be most similar to firearms, sirens, angry voices, and shouts of pain or fear.
The researchers suggest that the Aztec Death Whistle might have been built to mimic some natural sounds like screams and reproduce the effect that this has on the listener.
Previous studies have shown that the death whistle works by producing multiple tones at once as air collides within its different chambers.
By analysing the acoustic profile of different whistles, the researchers found that the resulting ‘noisy and rough’ sound profile contains effects usually found in primate screams and ‘terrifying music’.
The fear factor is made more intense by including tones typically found in human speech and shouts.
However, the researchers also noticed another interesting detail in the listeners’ responses.
In addition to reporting how the sound made them feel, each participant was also asked to come up with a description for the sound.
Participants who heard the Aztez Death Whistle (labelled in red as SW) reported experiencing high levels of negative emotions (valence), strong emotional arousal, and an intense feeling of urgency
A human scream was the most common comparison.
However, participants also referred to a number of artificial sounds like kettles, chainsaws, trains, or machines.
In their paper, published in Communications Psychology, the researchers suggest that this unusual mix of natural and unnatural could be part of why the Aztec Death Whistle is so scary.
Professor Frühholz says: ‘With fMRI we found that the sounds have both an affective [emotional] nature and they have a more abstract and symbolic nature, which triggers associative mechanisms in the brain.’
When a listener heard the Death Whistle, this set off a flurry of activity in the brain’s auditory processing regions as it tried to determine the origins of the sound.
This sudden activation tended to confuse the brain, leaving it momentarily stunned and confused.
The Aztecs may have exploited this shocking impact as a way of creating fear in an audience.
However, archaeologists are still unsure whether that audience was intended to be an approaching enemy army or a congregation of worshipers in a human sacrifice cult.
Researchers have found that the terrifying sound of the Aztec Death Whistle (pictured) is just as terrifying to modern listeners as it would have been to the Aztecs more than 500 years ago
Since the sound is so scary it could be the the case that the Death Whistle was used in warfare but Professor Frühholz and his co-authors believe that the ritual explanation is more likely.
Aztec Death Whistles have been found in the hands of victims of ritual sacrifice in temples such as the Ehecatl-Quetzalcoatl temple in Mexico City.
Likewise, the skull imagery synonymous with the Aztec Death Whistle could portray Mictlantecuhtli, the Aztec Lord of the Underworld.
In their paper, Professor Frühholz and his co-authors write: ‘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.
‘Skull whistles might have been used to scare the human sacrifice or the ceremonial audience, but further cross-documentation is needed here.’
