From Unofficial Handbook of the Virtue Universe
Characters in this category are accomplished vocalists. This can also cover characters with Sonic power sets who use them to perform, including anthropomorphic or animal characters who use their cries in an artistic/performance sense (a wolf's howl or a whalesong, for example).
A certain degree of commitment is required to distinguish a singer from somebody who simply messes around with sings - a lot of people sing in the shower, but wouldn't consider themselves singers. It's not necessary that the character perform in a professional capacity, but it should at least be considered a passion of their's, or an important hobby.