Like this : imagine a sound. For example, a cat meow. Meow meow. You doing that? Are you “hearing” that meow in your “mental sound space”?
Now imagine the sound is 500x louder. And it isn’t a meow, its an explosion.
It sounds like the blast of compressed air when you disconnect a compressor fitting.
That’s what it’s like.
It happens in half-sleep.
I’ve had big blasts that make me go “woah” a couple times a month since forever. I had a really big blast that made me go “holy shit!” just a couple days ago.