Formed in 1974 by three of Norway's best instrumentalists (Stig Nilsson, violin, Aage Kvalbein, cello, and Jens Harald Bratlie, piano), the Oslo Trio makes a rare Ame rican appearance as part of the "Chamber Music at North Park" series. The group's Chicago debut will spotlight the Nordic music for which they are so well known, including Edvard Grieg's rarely heard Andante con moto in C Minor--one of a mere handful of Grieg chamber scores, and Lasse Thoresen's Bird of the Heart. Thoresen is Norway's most gifted and most celebrated young composer (the two do not always go hand in hand), and he combines such diverse compositional techniques as serialism, minimalism, and structural permutations, along with jazz and rock elements. Bird of the Heart reflects all of these, and is also indicative of Thoresen's highly personal, phenomenological approach to music, with virtually every colorful phrase bursting forth with a spiritual as well as aesthetic meaning. Also on the program is the Tchaikovsky Trio in A Minor. Tonight, 8:15 PM, lecture hall auditorium, North Park College, Foster and Kedzie; 583-2700, ext. 4300.