During the film, when the troglodytes are close, we often hear this eery screeching noise. When we actually see them on screen, towards the end of the film, we learn that this is their method of communication.
They appear to have some sort of object embedded in their wind pipes, which warps their sounds making them much more screech like (like having a whistle in your throat). One of the protagonists cuts this object out of a dead troglodytes' throat and uses it to "summon" other troglodytes to him, so he can kill them.
It's all very fascinating, and very brutal, but I was curious to know if this object in their throats is remotely realistic.
Has there been any cases of ancient tribes of Indians (or other races) found with similar contraptions? Is it even possible to have a device like this actually embedded in your throat?