Getting irritating notification sound - how to turn it off?

[AC Question]

Some app is producing a notification sound or something on my phone, and I have no idea what it is. Some icons leave a new email or new message icon, but whatever is doing this is leaving no trail. I thought it might be Facebook, but I'll check it after I hear the sound and I don't see a new message. I also checked that app's notification settings, and I don't see any notifications turned on. I feel like a victim with this sound, and I have to turn my volume all the way down during the day to shut it off. Of course, that defeats the purpose of having a phone in the first place.

 

[belodion]

Try Safe Mode, which temporarily disables all third-party apps. That will narrow it down a bit.
Get back to us if no go.

 

[Crunchyhippo]

Sorry for the delay - I'm trying to sell my house. If I stay in safe mode and the notification goes away, all it'll tell me is that it's an app; not which one it is. This notification may only occur every other day. Will staying in safe mode keep me from doing things I could normally do on a day-to-day basis?

 

[Crunchyhippo]

I'm getting this sonar-like notification sound every day now - sometimes at 2:00 in the morning when the phone is by my bed (I have to keep it there; my parents are old). And because I'm a light sleeper, this notification always wakes me up. I can't turn the volume down because I need to hear the ringer in case I'm called for an emergency. This really sucks.