I had this problem of constant notification tone going off repeatedly (seemed like every 5 minutes or less), yet no new notifications, texts, emails, etc. It was driving me crazy. This is with my note 3. I had this problem when I first set up the phone but managed to get it to stop, only to have it start back up again yesterday. I only like notifications for texts and calls. Don't want them for email, Facebook, or anything else. Apparently 4.3 has this persistent notification feature that can be impossible to shut off even after you go into app manager and uncheck "show notifications." I figured that because it started back up again yesterday that it must be due to a recent app I downloaded. I, one by one, uninstalled my recently installed apps, waited, heard the notification tone, reinstalled that app and went to the next app to uninstall. The culprit for me was light flow (probably because I didn't take the time to properly set up for what I want.
Long story (I'm good at that) short, try uninstalling recently installed apps. If one of those is the problem, you can either carefully go through all those apps settings or leave that app uninstalled.
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