“Death whistles,” or Aztec skull whistles, were short, carved instruments made of two opposing chambers where air could clash ...

Brain scans of modern listeners suggest that Aztec whistles sound like human screams, which may have prepared sacrifice ...

But in the forests of central Mexico, a single note from an Aztec whistle didn’t always indicate celebration — it meant death. “Death whistles,” or Aztec skull whistles, were short ...