This has happened to me a few times being woken to a small siren noise that gets louder and louder and then just stops. Or a scream that starts of faint and then out of nowhere is the loudest thing I’ve ever heard leaving my ears ring

Now that I'm thinking about it, I would say the sound I hear would be a very loud "slam".
Interesting question 🤔...?...

I think I experience the same thing!! Not often, and actually haven't really ever put to much thought into it, other than "chalking it up" to another symptom of Narcolepsy.