What exactly does the heartbeat sound mean?

[CoyoteTraveller]

I know that during a ghost event with an apparition, it means you're looking at the ghost and losing sanity. But sometimes, when I'm hiding in a closet and the ghost is walking past, I get the heartbeat just standing there with the doors closed. So is it something other than "line of sight to the ghost"? Or are some closets bugged so you can get LOS through them?

[Captain Masterson]

I would like to know this as well. Ill be in a closet, and undetected by the ghost as it walks past and the heartbeat sound begins playing.

[dsaw]

i think it just means you're being hunted

[Boogie]

It just means it's near you.

[Borath]

As far as I have been able to figure out, its LoS and proximity.
The ghost has to be somewhat near you and your vision cone has to be looking in its general direction.
and yes, you can have LoS to the ghost past walls but the ghost wont have LoS to you.

[Noelle]

Doors and windows are transparent for the purposes of determining your line of sight to the ghost. (Not so much for the ghost.)

[Kelrycor]

The heartbeat does only mean that the ghost is in line of sight from your vision during a hunt or spook. Though you must not face it though.

It can happen through doors or windows, or if the ghost somehow "clip" a little bit through a locker door while passing.

It does not mean the ghost actually saw you or is chasing you.

Also it has a certain range. You will notice this in very long hallways, like High School.

[CoyoteTraveller]

Awesome, thank you all!