Sup /x/, check 7:45 of this video:
This channel is some guy who just explores abandoned mines for fun and has a lot of previous videos, none of which are paranormal at all, and you can tell he's geniune about this and isn't the kind of person who would be bothered to try and hoax it.
The voice seems to be coming from a PA system.
It seems to say
>why are you here?
>you should get out
The rest is inaudible, the alarm seems to be ones typically used in mines.
Very spooky 10/10 because it seems authentic. Even the way he talked, you could tell he was genuinely scared.
I doubt that, plus who has something that sounds like a p.a. system for cave exploring.