The Ghost Child's Potty Skills

In the middle of the night I heard an unidentifiable sound, something like a cell phone jingle or a game which sounds a tune when you get the answer right.  I thought maybe our recent guests had left their cell phone behind or something.  A few minutes later it sounded again and this time I recognized it as the noise that Daniela's potty chair throne makes when she goes potty on it.

I tried to think up a scenario that would make the potty chair go off without someone peeing in it, but nothing logical came to mind.  Perhaps we had a ghost child in the house practicing their potty skills.  Just about the time I was about to fall asleep the potty made several congratulatory trumpet sounds in a row and then I could hear Ashley in the bathroom frantically taking the potty apart trying to stifle the commotion before it woke up Daniela.