As scary as something may be, hearing it before you see it can heighten your own fear. "What is that, where's it coming from, am I gonna die" are reasonable, if dramatic, reactions to mysterious and gruesome sounds, many of which are not easily forgotten.
The rasping gurgles of people dying, animals screeching before slaughter, noises with no clear point of origin, they can all haunt your reality as easily as your dreams. The stories told here, all from Reddit, are of real-life experiences of auditory horror; some end humorously, others somberly, but all of them begin frighteningly.
I was working a bad accident where a person had skidded down the pavement. I thought they had passed and when I got up to him/her they grabbed my arm.
Most of the skin and cartilage had been sanded off and the person mostly gurgled and spit before finally slipping away. That was almost 10 years ago and I still have nightmares.
Foxes screaming at 3 am outside my bedroom window. It was terrifying when I didn't know what the sound was at first, sounded like someone dying in the street.
I used to live on a cattle farm in Ohio, where there was something of a dog problem. People got dogs they couldn't care for and instead of taking them to the pound like they were supposed to, dropped them off in the middle of nowhere, IE, where we lived.
The dogs would grow up to be incredibly violent and hateful. Then they got busy with another local problem: the coyote population. With no real predators, and nobody interested in hunting them for meat or pelts, coyote population had a tenancy of getting extremely top heavy. They'd scavenge fine for a year-or-two, but eventually there was too much competition, and they'd start to hunt.
So, you have incredibly violent and hateful dogs, whose size runs the gambit from being roughly the same as a coyote, and as big as a juvenile black bear, and coyotes, who now have competition problems and trouble getting enough food. And they're compatible. Coydogs may not be able to breed themselves, but a female can put out quite a few of them. This led to years where the area was infested with incredibly violent and territorial "tribes" of feral/wild dogs, Coyotes, and half-breed coydogs, all in an area that raises cattle.
To get to the question, my dad and I were out hunting the dogs (we'd get money for each one we killed) one night, and heard a pack corner a fairly large cow. That cow's screams were absolutely nightmarish. We kept trying to get to it, but due to the way the sound echoed, we just couldn't find it. That thing did nothing but scream for almost fifteen minutes. By the time we found it, the dogs had stripped it damn near to the bone.
When you go to the dentist and have to have a tooth extraction, and that sound of your tooth cracking as it's being pulled out.