Probably 10 years ago, I read a young adult book that I cannot remember the title or author of. I also cannot remember the names of the characters. However, I can recall nearly the whole plot.

The main character is a girl who lives in a community that has rebuilt after the devastating sound wars. To avoid another sound war, they no longer sing or make music. They also all wear masks that they receive as young adults, to stay unified. Before they get their masks, they color a coat according to their ability by humming into a machine. The girl, however, does not seem to have a talent. She can see sounds as colors, but does not realize this is a talent, she just assumes everyone can do it. The girl is told that she will have another year to find her talent, but then she gets in trouble for sneaking in to watch the masking ceremony. She ends up having to work as a maid because of this. Then she does something else wrong and, to keep from being punished, she ends up running away outside the walls of her community. She finds a group of people who live outside the walls, and they teach her the true history of how the sound wars happened. The girl realizes that the people who are controlling her old community were the bad guys. She returns to save everyone, has an epic battle, and ends up using her gift to eventually conquer the corrupt rulers and free her people.