Aztec death whistles do not suit any existing Western category for wind instruments; they appear to be a distinct sort of “air spring” whistle, based upon CT scans of a few of the artifacts. Sascha Frühholz, a cognitive and affective neuroscientist at the University of Zürich, and numerous coworkers wished to discover more about the physical systems behind the whistle’s unique noise, in addition to how human beings view stated noise– a field referred to as psychoacoustics. “The whistles have an extremely distinct building, and we do not understand of any equivalent musical instrument from other pre-Columbian cultures or from other historic and modern contexts,” stated Frühholz.

A symbolic noise?

For their acoustic analysis, Frühholz et al. acquired sound recordings from 2 Aztec skull whistles excavated from Tlatelolco, in addition to from 3 sound whistles (part of Aztec fire snake incense ladles). They took CT scans of whistles in the collection of the Ethnological Museum in Berlin, allowing them to produce both 3D digital restorations and physical clay reproductions. They were likewise able to get 3 extra artisanal clay whistles for speculative functions.

Human individuals then blew into the reproductions with low-, medium-, and high-intensity atmospheric pressure, and the occurring noises were taped. Those recordings were compared to existing databases of a broad series of noises: animals, natural soundscapes, water noises, city sound, artificial noises (when it comes to computer systems, pinball makers, printers, and so on), and numerous ancient instruments, to name a few samples. A group of 70 human listeners ranked a random choice of noises from a collection of over 2,500 samples.

The CT scans revealed that skull whistles have an internal tube-like duct with a restricted passage, a counter pressure chamber, a crash chamber, and a bell cavity. The uncommon building recommends that the standard concept at play is the Venturi impact, in which air (or a generic fluid) accelerate as it streams through a restricted passage, therefore decreasing the pressure. “At high playing intensities and air speeds, this leads to acoustic distortions and to a rough and piercing sound character that seems uniquely produced by the skull whistles,” the authors composed.