Northwest Chamber Chorus marked its 40th anniversary with a gold-medal performance of composer Joan Szymko's "Carpe Diem."

Concert review |

If you think choral music makes for easy listening, you should have heard the Northwest Chamber Chorus performing its 40th-anniversary program at Town Hall Sunday. The experience was like watching an Olympic figure-skating championship — thrilling and a bit nerve-racking. In between some dramatic pyrotechnics, smooth gliding and subtle artistry, there was an anxious moment here, a wobbly landing there. Despite these, the chorus made an unmistakable case for itself as a musical force to be reckoned with.

In a sense, three different choirs sang: the one that poured out a gorgeously fluid Rachmaninoff under the direction of guest director Steven Demorest; the one that painted a delicate woodland watercolor of a Monteverdi madrigal with guest director Joan Catoni Conlon; and the one that, with present director Mark Kloepper, turned “The Battle of Jericho” into a lively mini-epic so visceral you could almost see the dust rise up from “the walls a tumbalin’ down.”

There was, actually, another chorus that performed, when more than 30 past members of the ensemble joined the present body of 39 onstage for a rousing, heart-swelling rendition of the Christmas motet “O Magnum Mysterium.” The increased numbers prevented in this piece some of the unevenness that crept into the end of the demanding J.S. Bach and Rheinberger’s “Kyrie.”

When the words being sung are in a language not native to the audience, their sound becomes more significant than their meaning. And any blemish in tone or phrasing — however slight — becomes more noticeable. This holds doubly true when the only word being sung is “Alleluia.” Thompson’s “Alleluia” offered a fascinating case study of this phenomenon: The choir’s performance of it occasionally switched off and back on again in clarity, almost like a cellphone with faulty reception.

These are quibbles, though, compared with how well the choir executed what amounted to the triple axel on its program: the world premiere of Portland composer Joan Szymko’s “Carpe Diem.” It’s not easy to perform a piece no one has ever heard before for the precise reason that no one has ever heard it before. There is no expectation to live up to or work against. Despite this lack of context, the group spun a rich, compelling tapestry of deliberately bent edges and artfully frayed lines. Against this backdrop, soloist Jean Robb stood out in achingly pure relief. This piece was obviously well-rehearsed — a gold-medal moment in a silver-medal evening.

Sumi Hahn: sumi@bewodo.org