When I was around 15-16 I think, we used to live in an apartment. It was the 5th floor I think, it was pretty high. I'm including this detail because it might be relevant.
Now one night, just like any other night, I'm sleeping in my bed. But I wake up, and I'm terrified.
I'm terrified because I'm hearing thousands and thousands of humans screaming in pain and agony. They are howling like mad dogs. I'm looking at my white painted wall, barely breathing. I'm so scared I can't even dare to move a muscle.
I don't know what to do, and the cacophony continues. I eventually close my eyes and pretend I'm not hearing anything at all, but it's there.
I fell asleep after. Next morning I wake up, tell my mother, she doesn't really believe me. Actually nobody believes me. Nothing supernatural happened after that. I think maybe the wind was causing the sounds and I misheard it, but I don't know.
Here's how it sounded like:
It starts at around 2:00, it was something like this, but with more women screams.