The death rattle works because no genre vocabulary domesticates it
Kayako's croak in Ju-on — clinically, a death rattle, the sound of fluid pooling in the throat of someone actively dying — was created and personally performed by director Takashi Shimizu. The camera doesn't need to show Kayako. The rattle is enough. But the reason it's enough is specific: the body processes this sound before the conscious mind classifies it, because there is no horror-genre template for it. No amount of watching horror films conditions you to hear a death rattle as "just a movie sound."
The masterstroke is the copy-machine scene. The mechanical hum of the copier slowly, seamlessly transforms into the rattle. This isn't a transition effect — it's the film's thesis at the audio layer. The curse is biologically infecting the modern environment. Office equipment becomes a body becomes a mouth. Once you've heard it, every copier is suspect.
This is also why the rattle survives translation when almost nothing else does. The American Grudge keeps it, and it keeps working — not because American audiences understand kegare or ma, but because death rattles predate all genre conventions. The nervous system has always known what that sound means.
A sound the body should not make outside of one specific context (active dying), deployed in a copy-machine room, is processed by the listener before conscious classification can intervene. There is no genre vocabulary that domesticates this. That's the mechanism — and it's why it survives translation when nearly everything else about J-horror doesn't.
Source claim: The death rattle survives transplantation into American remakes because it bypasses genre conditioning entirely — the nervous system responds before the conscious mind can classify it as a horror convention.