Students will raise their voices to promote healing in the world at Kol HaNeshama, the Day School Music Festival, on Sunday, December 18 at 4:00pm at Gann Academy, 333 Forest St., Waltham. Hosted by Solomon Schechter Day School of Greater Boston, the event will also include performances by students from Boston’s Jewish Community Day School, Gann Academy, Kehillah Schechter Academy, Maimonides School and Metrowest Jewish Day School.