Ensemble Project Ars Nova, or P.A.N., specializes in the “new art” from which it takes its name: the intricate polyphony that first emerged in the early fourteenth century. Most listeners today classify such music as ancient, but to P.A.N.’s singers and instrumentalists, the passions and anxieties it captures resemble those of our own millenarian age. Perhaps to press that point, P.A.N. has recently released a fascinating album called Unseen Rain (New Albion), consisting of new music steeped in the technique and aesthetics of new music 600 years old. The composer is Robert Kyr. From December 1 to 12 the ensemble visits Pittsburgh; Caldwell, Idaho; Moscow, Idaho; College Park, Maryland; Dumbarton Oaks, Washington, D.C.; and Boston. For more information see local listings.