While Harrison Birtwistle has long been established as a composer of major works for the theater, he has maintained a connection to the humbler spheres of vocal and chamber music, writing modestly scaled works that, in substance and mood, are rarefied, reflective, and intimate. The two groups of settings of the poetry of Lorine Niedecker, composed for soprano and cello, have a spare quality reminiscent of Webern, and they possess a quiet, meditative stillness that comes from simplification of accompaniment and concentration of expression. Bogenstrich: Meditations on a Poem of Rilke, for voice, cello, and piano, is more richly textured and sometimes chordal, and though there are fleeting allusions to Romantic art song, the style is uncompromisingly modern. The Trio for violin, cello, and piano is unusual for Birtwistle because has avoided conventional instrumental groupings since he composed his Refrains and Choruses for wind quintet in 1957. Yet his handling of the violin and cello as independent parts, disconnected from the piano except for brief intersections of activity, is his solution to the problems of using such a standard ensemble and its attendant expectations. The somber performances by soprano Amy Freston, baritone Roderick Williams, violinist Lisa Batiashvili, cellist Adrian Brendel, and pianist Till Fellner, produce an introspective mood, and the subdued program is stock in trade for ECM New Series.