More from the article...

... Brain scans suggest the whistle's tones may do more than create a scary ambience. Swiss and Norwegian researchers found hearing them activates a variety of higher order centers in our brains, suggesting a complexity to the sound that can only be described as an alarming mix of the natural and the eerily unfamiliar.

It's no wonder the Aztecs likely used them to enhance religious and sacrificial rituals. ...

... the sound of the Aztec death whistle is as creepy ...

Judge for yourself.

From the link provided for "the sound" ...