A promising new series of free vocal concerts got off to a shaky start Tuesday night in the Harris Theatre at George Mason University. Soprano Rosalind Gnatt, expertly accompanied by pianist William Huckaby, gave a well-planned but unevenly performed program of music by Schubert, Brahms, Wagner, Mahler and Richard Strauss, sampling a substantial part of the stylistic variety available in the German soprano repertoire.

Can she be a mezzo-soprano aspiring to higher things? It is impossible to say on the basis of one recital, but she sometimes gave that impression, showing much better control of pitch, dynamics and color in her lower register than in her sometimes erratic top notes.

In this program, Gnatt's talent often seemed more dramatic than lyric. She was at her best in songs that had a strong theatrical element, such as Brahms's "Vergebliches Staendchen" ("Unsuccessful Serenade"), which is a dialogue between a suitor out in the cold and a young lady who keeps her door firmly locked, and Mahler's "Das Irdische Leben" ("Earthly Life"), a dialogue between a helpless mother and her child who is starving to death.

The performance was most vivid and comic in the last number on the program, Mahler's "Lob des Hohen Verstandes" ("Praise of High Intelligence"), in which she gave a vivid imitation of a singing competition between a cuckoo and a donkey.