Brain scans of modern listeners suggest that Aztec whistles sound like human screams, which may have prepared sacrifice victims for their journey to the underworld.

Others think they may be relics from the legendary island of Atlantis or proof that extraterrestrials visited the Aztec sometime before the Spanish conquest. Stories about the skulls focus heavily ...

Aztec death whistles, or skull whistles, are small clay creations ... turbulence to produce the frightening sound. Scholars have long debated over the purpose of the whistles.