Was a time, we just threw these kind off of cliffs. I know. The old ways were better than what we have today.
Sounds like a scream, right? It is designed to call forth demons when the child is about to be slaughtered. These death whistles are used against the victim, by blowing that scream into their head. It's quite ugly.
She is summoning demons. It's akin to a spirit bell. A small hand held bell that witches use to summon demons and familiars. You see a small bells or a bell in a home, you are among witches. FYI
https://yeshuafreedom.com/w/roMyPrbiJEbd6AdF9QaDz7