Well, 'Music of the Heart' isn't a true story. It's more like a creative composition that aims to touch the hearts of the audience through an invented narrative and characters.
One key element is Roberta Guaspari's determination. She was very determined to bring music education to the kids in Harlem. Another is the impact on the students. They were transformed by learning the violin. Also, the community's reaction was important, from the initial doubts to gradually supporting the music program.
I'm not sure if there's such an actor. However, if you are asking about the music teacher in the movie, I can tell you that the role is played by Eason Chan.