The Danish Wave '99, which has been picking up momentum over the last few weeks and runs through the end of the month, is a collaboration between the Danish Consulate and arts groups in New York, its aim being to introduce the city to music (classical and jazz), theater, film, photography and poetry from Denmark. As a part of the series, Ars Nova, a 12-voice a capella choir, is giving a handful of concerts in New York, the first of which was on Thursday evening at the Church of St. Ignatius Loyola. It is also performing tonight at St. Paul's Chapel at Columbia University, and at St. Vincent Ferrer Church (Lexington Avenue at 66th Street) tomorrow. Because its name refers to a 14th-century stilistic movement, one might expect Ars Nova to be an early-music ensemble. But the group seems to be taking its name more literally than historically, at least some of the time. Although its program included some early music - sweetly blended readings of motets by Byrd and Obrecht - most of what it sang was of more recent vintage. There were, for example, two pieces by John Cage, although listening to Ars Nova's ravishing, orderly performances, set in the extraordinarily resonant acoustics of the church, one would have been hard pressed to identify Cage as the composer.

In "Four2" (1900), the choir deployed itself in groups of three. Cage provided the notes each group was to sing, but how long they sustained them was the performers' choice. Here, the singers created a slow-moving chordal cloud. In "ear for EAR - Antiphonies" (1983), a solo singer sang a plaintive line at the front of the church; the rest of the choir responded from the back in a harmony that would not have been out of place in 1600. Pelle Gudmundsen-Holmgreen's "Statements" (1969), the first of two Danish works on the program, is a clever game piece. The text consists of only a few words, but each word is given its own note or musical phrase. As the words are shuffled and recombined, the notes follow along so faithfully that after a verse or two, a listener could predict the melody. Hans Abrahamsen, a student of Mr. Gudmundsen-Holmgreen, was represented by "Universe Birds" (1973), a fascinating cluster piece for five sopranos that had an eerie effect as the overtones cascaded around the church. The program included Arvo Pärt's introspective "Magnificat" (1989). Paul Hillier drew a consistently ravishing sound from the singers.