Amazon.comPlainchant ("Gregorian" chant) was not strictly a medieval phenomenon: new chant melodies and even repertories were composed well into the 18th century. Marcel Pérès and Ensemble Organum perform here selections from an 18th-century chant book from the cathedral of Auxerre in southern France. They have also tried to re-create the practice of improvised harmonization of the chant: the effect (as heard here, at least) is sonorous and a bit wild--something like plainchant in sacred harp style. As with several of his endeavors in recent years, Pérès uses the indigenous polyphonic singing of Corsica as a reference point; this disc is more convincing than Pérès's other such efforts. --Matthew Westphal