This is a pretty amazing discovery! Sadly due to the conquest and subsequent colonization so much of the Aztec way of life and customs have been lost. The death whistle is a prime example we don’t know what it was for!
Swiss and Norwegian researchers found hearing them activates a variety of higher order centers in our brains
The skull whistle in particular activated the inferior frontal cortex, which deals with elaborate classification processing, and the medial frontal cortex, a region involved with associative processing.