What is the importance of the church organ in the short-story, The Wedding-Knell?

The church organ symbolizes the bittersweet triumph of accepting one’s death. As the wedding ceremony proceeds, the church organ plays a somber tune to match the tolling bell. However, by the end of the ceremony, the organ is playing a happy tune. It is loud enough to drown out the bell, thereby representing the counter-intuitive triumph of the characters accepting their fate.