The Locrian Chamber Players, a contemporary music ensemble now in its sixth season, has just one operating principle: to perform music written only within the last 10 years. This might seem a needlessly restrictive policy. But viewed another way, it represents the Locrian's refreshing conviction that there is plenty going on in the present to keep its programs lively.

Though the Locrian has a regular roster of players, the program began with a featured composer, Neal Kirkwood, performing his own "Five Variations Without a Theme" for solo piano. Steeped in the 12-tone idiom, though not in any strict way, the work began with skittish gestures, separated by long static silences. It became more interesting later with some wistful, tonally tinged episodes of undulant repetitive patterns.

By choice, the ensemble does not provide program notes. Perhaps a new piece should be able to stand on its own, and audiences compelled to trust their intuitions. On the other hand, it would have been interesting to know what Mr. Kirkwood's intentions were in this work, which finally left no strong impression.

It did not help that Mr. Kirkwood's piece was followed by a riveting work by a living master: Gyorgy Ligeti's "Sonata for Solo Viola," played by Scott Rawls. The first movement starts with an earthy, folkloric melody, rather like the tunes Bartok discovered during his travels through remote Eastern European villages. Before long Ligeti doubles over and develops the tune in ingenious ways. The vivacious "Loop" movement should be played "with swing," in the composer's words. But swing here means something jerky and dangerous, not jazzy. There is a brusque lament and a harmonically pungent final "Chaconne chromatique." Mr. Rawls's performance was musical, dramatic and deeply felt, but not entirely confident technically. He may still be learning the work, since he omitted the undoubtedly difficult Presto movement, which is marked "As fast as possible."

The Tokyo-born composer Jo Kondo was associated with John Cage during the 1970's, and his "Three Songs of the Elderberry Tree" for violin (Katie Lansdale) and percussion (William Trigg) had a Cage-like quality, with its meandering, microtonal melodies against a delicate backdrop of bell sounds and tapped drums. Mr. Kondo's "Short Summer Dance" for piano was far more inventive: restless, astringently atonal, yet wispy and gentle music, played beautifully by Emily Wong.

The Locrian Players might rethink their policy of not providing program notes, for it proved immensely helpful to have the final work, "Timing," for two percussionists, introduced by its soft-spoken composer, David MacBride. The work was inspired, he said, by listening to his baby's heartbeat in utero (about 150 beats a minute) alongside his wife's (about half that). "Timing" is a sound portrait of their shared existence. To the mix of percussion instruments Mr. MacBride adds a kitchen timer, ticking away, amplified just enough to be audible, representing the gestation period.

The beguiling music alternates soft rumblings on the drums, played with bare hands and fingers, with pummeled outbursts produced by sticks, and a wondrously delicate myriad of sounds from tin plates, glass dishes and rattles. After the final flourish on the drums, the fine percussionists, Evan Hause and Mr. Trigg, held their arms frozen in place as everyone waited for the timer to run out. "Clink" went the bell and the piece was over.

You wanted to hear the work again. But don't count on the Locrian Chamber Players to reprogram it. "Timing" was composed in 1991, so it just sneaked in under the ensemble's 10-year-cutoff policy.

(Anthony Tommasini )