Divine Songs: Ockeghem@600

Blue Heron, the esteemed choir from Boston directed by Scott Metcalfe, is midway through its Ockeghem@600 mission to record and perform the composer’s complete works. This program’s lovely Missa sine nomine a5, based on a plainchant melody, has only three movements: Kyrie, Gloria, and Credo. In addition to songs by Ockeghem and his contemporaries, the program also features a six-voice setting of the Salve regina by Obrecht.