I respect the rigor here, but I can't imagine "scary scream like noise was used to spook people" is a novel idea to anyone. The main interesting point to me is that it was categorized as both manmade and non manmade. If you wanted a scream you could just make one yourself. So I suppose the utility of the instrument is that the scream sounds human like but obviously isn't, adding some fear of the unknown into the mix?

ESR has a theory:

"The factual piece missing from the article is that sacrificial victims were drugged into semi-consciousness so they wouldn't struggle and disrupt the ceremony.

This meant they didn't scream as obsidian knives were penetrating their chests and their hearts were ripped out to be offered to the gods. Obviously, the Aztecs considered the ceremonial experience incomplete without the screaming, and built death whistles to simulate the proper sound of agony." https://x.com/esrtweet/status/1859556171918479626

>If you wanted a scream you could just make one yourself.

I would personally find it really difficult to produce a scream that replicated the sound of abject terror produced by the whistle.

not everyone is a scream queen with the ability to make that kind or any thing close we've been trained to expect as a "scream". we've probably all seen movies with armies squaring off and then yelling as they charge each other in utter stupidity, but that sounds nothing like these whistles. give a charging army these to blow in as they charge, and it would be a totally different effect. use these while hidden in the tree line like in Macbeth so you had to imagine what the thing making the noise looked like and it would be even worse. way worse than any beating drum could do

psyops are to be thought of as a minor thing at your own peril