The third of the Summer Serenades at Rockville's Strathmore Hall last night brought an unusually varied program of chamber music played with exquisite attention to the special idiom of each piece. In various combinations, violinist Mary Findley, flutist Karen Johnson and pianist Dionne Laufman Weigert played music by Bach, Dutilleux, Poulenc, Mozart, Ibert and Brahms and a newly commissioned work by Haskell Small, all relatively lighthearted pieces appropriate to a warm summer evening, and each with its own special stylistic requirements.

The Bach Trio Sonata from the "Musical Offering" was exceptionally transparent, with the give-and-take of individual lines always in balance. Johnson was pleasantly cosmopolitan in the Poulenc Sonata, which was propelled with well-gauged momentum, but she was at her best in the Mozart C Major Andante, in which she carved each phrase with a beautiful sense of the shape of the line. Findley gave a fine, impassioned account of the Brahms "Sonatensatz" and Weigert played everything with a marvelous sense of motion and drama.

In its first performance, Small's duo for flute and violin was particularly impressive for its economical use of musical material and for its rhythmic drive. The instruments imitate each other closely, sometimes tripping over each other's heels, and there are elements of fun and of teasing in its makeup. The performance was well coordinated and secure.