Polyphonic Challenge. I, Magistra Isabeau d’Orleans issue a challenge to group performers for a performance of a piece from before 1600, in three or more parts for voices, instruments, or a combination of both. The group will be judged on intonation, musicality and period performance practice. The more you can transport us back in time, the better! Those who complete the challenge will be able to select from four packets of a selection of pre-1600 music.