phantom tone started about 2 weeks ago

[aa777rob]

i noticed about 2 weeks ago the phone must have done a major update. Youtube looked different, a few other querks i noticed were different, but about that time i started getting a randon chirp for no reason. when looking at the phone when it happens, there's no popup indicating anything. i added an app that tracks notifications but it shows nothing, there are no new emails, there are no voicemails waiting, im baffled!! the tone isnt one used by any of my notifications, so im at a loss. anyone else have this happen? if so how do you stop it!? it's about once an hour at randon times. never the same minute mark.