Strange noise

So I’m driving to Sears Point and I keep hearing a strange sound. It’s kind of like a whirring sound with about a three second frequency on, off, on……….. Not real loud and not relative to either road wheels on engine revs.
I stop at Ferrari of SF and ask if anyone has any idea. No one has a clue.

Then a few days later I hear the same sound in the Mercedes, Whoops……….It’s my hearing aids cycling. (insert embarrassed smiley here)