Has anyone been experiencing music coming from the tv while watching tv?

I know this is going to sound ridiculous but I have to ask.  My 94 year old mother has been claiming for the last 5 days that she is hearing someone playing and singing the song "Silent Night" from the tv while she is watching tv shows. It doesn't matter what channel or what show she is watching, it just keeps going on and on, over and over. I go in to her room and listen whenever she says it's happening, but I don't hear it at all.  She is getting angry that I can't hear it and she does. She wants me to call Xfinity to come out and check it, but I just can't imagine that they would hear it either. My mother has not shown a single sign of dementia or being senile or any other old age thing, so I just don't get it!  Anyone else hearing music?