What does this sound mean?

[BuIlDaLiBlE]

During gameplay when someone is near you that looping bell-like sound starts to play. Might be a dumb question but I honestly dunno what it means. Btw if you don't get it then you can hear it at this moment for example: https://youtu.be/RictfMEcEjI?t=4m26s.

[Hunter #357]

That means that either...

1. Foxy, Freddy, Toy Freddy or Golden Freddy is in the hallway.

2. Bonnie, Chica, Toy Bonnie, Toy Chica or Mangle are right outside the vents.

or

3. BB is in the vent to your left.

[BuIlDaLiBlE]

Originally posted by Hunter #357:

That means that either...

1. Foxy, Freddy, Toy Freddy or Golden Freddy is in the hallway.

2. Bonnie, Chica, Toy Bonnie, Toy Chica or Mangle are right outside the vents.

or

3. BB is in the vent to your left.

Knew that has to do something with animatronics being near! Thanks for the detailed info.

[JockeyField]

but like, WTF IS THE SOUND?! WHAT WOULD CAUSE THE SOUND! YOU SAID IT SOUNDED LIKE A BELL BUT WHY WOULD A BELL BE IN A PIZZERIA?! WTF IS THAT SOUND?!

[Rainbow Spy]

Originally posted by The Combine:

but like, WTF IS THE SOUND?! WHAT WOULD CAUSE THE SOUND! YOU SAID IT SOUNDED LIKE A BELL BUT WHY WOULD A BELL BE IN A PIZZERIA?! WTF IS THAT SOUND?!

I have a theory that maybe it's the guard panicking in sound form. I highly doubt those big bulky animatronics have any form of stealth in their footsteps

[Freeze_Zane06]

It just tells that someone is in the hall

[Chromatic]

Hi there! Freeze_Zane06 is right - the noise is an audio cue indicating that an animatonic is in the Hallway outside the Office. Have a nice night!

[Mr. Wick]

The sound means:
Someone is either in or entering your hallway or vents.

[Masked Stickman]

Originally posted by The cool heavy:

but like, WTF IS THE SOUND?! WHAT WOULD CAUSE THE SOUND! YOU SAID IT SOUNDED LIKE A BELL BUT WHY WOULD A BELL BE IN A PIZZERIA?! WTF IS THAT SOUND?!

its most probably something like the ambience 2 audio from fnaf 1

[𝓟𝓸𝓹𝓹𝔂]

It's actually a security alarm, listen closely, it's echoing, it isn't just a haunting music, fnaf 2's security spiked up a lot, this is evident due to the fact that the new animatronics have a facial id that can detect predators, there is no need for shutting the power off at night either,

I noticed, that the alarm only plays when there is actual player risk, when you don't hear the alarm,b ut an animatronic is in your hallway, you're actually safe, it's when you hear the alarm is when you're in danger, it's meant to go off as if it's a motion sensor security system.

I actually just discovered this by myself, and shockingly, I don't think anyone noticed it, I was always wondering why that sound played, was it in his head? or just creepy ambient noise like the spook noise in fnaf 1? Turns out, it's just a security alarm.

Edit:
* It actually sounds more like what you hear in an old bank, their alarms typically sound this way, slow, grumbly, and loud.

See this for reference: https://youtu.be/D5tUHdUgAcI?t=367 this is an old building that someone was plundering, and they set off a security alarm, which sounds vastly different then the fnaf 2 noise, but, holds similar vain to the fnaf 2 alarm soundd, so the evidence that it's an alarm is quite likely,

Edit 2: I noticed some theories, so, I apologize if I took this thread a little too seriously, but I thought this fact was too interesting that needed sharing. So I do hope I was able to give some good info, and to give some facts over how it works.

[A Mongoose]

Just spooky ambience designed to tell you to get the heck out of cams.

[Kitsuki_White]

Ah yeah with the looping bell noise it means you have a visitor and will die if you dont do something quick. Can be anyone make sure to check your vents and hallway never forget to check your vents and hallway bc if its a habit through out the game, it'll be problematic on night 5,6,7, and the 20 mode especially

[Naziit]

Im new to fnaf 2 and exit every time i hear it, i dont know wether or not it means somebody is in the vent cams or in the vent light area.