there are couple sources of beeps - temperatue at 37* F, you get a note in the cluster
PDC beep from front or back, but PDC must be on,
top of the hour, tripple beep, but you already know it is not the case,
seat belt gong, not a beep
key in ignition gong,
lights on if not on auto, it is a gong too...

any warnings, are gongs with text in cluster, low washer fluid, low oil level...

radio? voice recognition? VR comes with text in cluster but there are so many variations out there, that it is hard to tell... try to hold the talking head button for several sseconds, lets see if it is the same beep...