A Chanter is an student occupation in Orum. It is related to the Druids of Orum. To promote harmony and continue the traditions of oral storytelling, children are offered up to study history and art in order to preserve their culture. It isn't so much a grand sacrifice so much as it is a type of schooling thought to be an honor. Any Orumian citizen is eligible to receive this education if they show potential talent in performing magic akin to a Bard.
A real-life parallel would be like sending a child off to get a prestigious private education. Somewhat of a Finishing School, they learn etiquette and poise, but also a fair amount of somatic-based spellcasting, history, and general studies of other subjects like humanities, economics, and psychology. In short, it's an education to ensure that the next generation is prepared to be introduced to society as an adult.