The National Musical Arts Ensemble opened its eighth season in residence Saturday night at the National Academy of Sciences with an artistically conceived program. Music for French horn, string ensemble and baritone made up the unusual evening.

The most familiar selection, Samuel Barber's "Dover Beach" (for baritone and string quartet), was sung with a slender but firm tone by William Parker. His expression was insightful and commanding. In four German and French songs, with pianist Patricia Gray and Laurel Ohlson on horn, Parker had trouble with intonation in the higher registers and did not sustain some notes long enough. Phrasing was anticipated nicely, however, especially in Berlioz's "Le jeune patre breton."

Violinist Rebecca Culnan and Paul Kantor offered vibrant readings of 14 of Bartok's "Duos." Largely based on folk elements, the collection of miniatures alternately crackled with explosive rhythms and plaintive melodies.

Beethoven's Sextet for Two Horns and Strings, Opus 81b, was rendered with a brisk and good-natured flavor. Culnan, Kantor and Ohlson were joined by violist Denise Wilkinson, cellist David Teie and additional horn player Sylvia Alimena in this seldom-heard piece. The adagio's warmth and smooth melodic lines were presented with particular skill.