Writing for string quartet and voice is a tricky thing, and at the basic level of craft, Jennifer Higdon skillfully avoids the pitfalls in In the Shadow of Sirius. The piece was played Saturday night at the Curtis Institute of Music in the first of this season's three residency recitals by the Aizuri Quartet at the school. Higdon, a Curtis composition professor, has a towering model for the form in "Dover Beach," Samuel Barber's moving 1931 work for the same combination.

In fact, Barber's language hovers near. The melancholy of "Dover Beach" can be heard in the first movement of Higdon's Sirius, and the American vernacular that makes his nostalgic Knoxville: Summer of 1915 the masterwork it is infuses the third movement of Higdon's piece, "Parts of a Tune." If this makes Higdon part of a continuum, it does nothing to detract from the originality of her work.

String quartet is at surprising risk for overpowering a singer, even one with as much of a presence as Rachel Sterrenberg, Saturday's soprano, and Higdon does a fine job of weaving the forces in such a way that the words of W.S. Merwin's poem are always understood. That third movement, "Parts of a Tune," becomes the lovely emotional heart of the set. Even without knowing it is about a man humming the same few notes while recalling an earlier time among the birds and trees, you can hear the music moving with all the inevitability of nature, the hymnlike tune in the strings, and the poignancy of his smile. Sterrenberg, a recent Curtis graduate, in perfect diction and soft smiling tone, drew beautifully vivid imagery.

The Aizuri's facility in two other difficult works bodes well for their other appearances here this season, at Curtis and with the Philadelphia Chamber Music Society. Berg's String Quartet, Op. 3 is a bear. But the players followed its intricate game plan with great skill, emphasizing alternating steel and Straussian melodic warmth. Beethoven is no less a challenge. The Aizuri seemed well on their way to uncovering the music between the notes in the String Quartet No. 6 in B Flat Major, Op. 18, No. 6. This is an ensemble of varied sounds and temperaments, a quality that they sometimes underlined, sometimes downplayed, but always used to great advantage in telling us who they are.