Tinkling bells

Yesyrtday at my wife's shop; she and a customer distinctly heard what sounded like small bells tinkling. It sounded like several bells , but the source of these tinkling bells could not be located. Checking outside, it was determined the sound could only be heard inside the store. She has no strands of bells hanging anyplace in the store. The ringing bells went on for several minutes and finally faded out. No source for these bells was found. I guess this is simply another page of the weird to be ascribed to this old structure.