I just realized this last night. Mildred is a character in an opera! That's why she sings about all the events in her life, and works on projecting her voice. After 18 years, she's gotten pretty good at it too. I can't hear the music, but it's a cat opera, so the bird cages are the orchestra pit.

This conjecture will be supported if Dinah yowls near the end.

P.S. 227.0.