Reverse beeping

I am new to the group and did a search but did not find anything on this. I have a 2012 TL AWD that has the reverse beeper as you get close(r) to an object behind/beside the car. Recently it beeps twice then pause, then beep twice over and over even if i am not approaching anything near the car. I have cleaned the sensors thinking maybe they are dirty but that did not eliminate the beeping. It does NOT do this every time i put it in reverse but probably 90% of the time. Anyone else have this occur and advice on the issue and how to fix it? thanks