How does Henry Reed change the tone of the graduation?

Henry Reed delivers his address to the class, as planned; then, he starts to sing the "Negro National Anthem," which is banned from being sung at public events. People join in and sing, and the condescension of Mr. Donleavy is purged. Maya is suddenly proud to be black, and feels a part of the black community for possibly the first time.

stand up and shout down the invited speakers