As part of their ensemble’s centennial tour, the singers who make up the St. Olaf Choir performed nearly two hours of exquisite choral music — in three languages and from memory — at Meymandi Concert Hall, and the sound from these 75-plus young singers was extraordinary. In fact, one of the most lasting impressions for those in the audience might well have been, “How did they do that?” How did they sing such music, much of it demanding, so well, and sing so well from start to finish? How did they sound so effortless in their singing, with crisp diction and fine dynamics, and how did they produce such rich and compelling sound without their energy flagging?

How did they do that?

Under the direction of Dr. Anton Armstrong, the group clearly showed why it is one of the best choral ensembles in the country. One end of this particular choral music spectrum might be occupied by the English cathedral choirs of men and boys, with their distinctive sound often led by the boy trebles, and at the other end of the spectrum might be found such professional or near-professional adult ensembles as the Mormon Tabernacle Choir, with its mass of 350 voices that puts out a full yet well-articulated choral sound. Bridging those extremes with skill, finesse and an unerring sense of musicianship would be a choir such as that from St. Olaf College in Minnesota. This group easily negotiates tricky rhythms and harmonies into an assured blend of youthful, supple and flexible voices, and when a full ensemble sound is required, the choristers deliver quite well. When unified sound from within sections is required, the choristers provide that, too. The sopranos, for example, can sound as if they are one singer; the deepest bass voices provide an unwavering foundation in the lowest register.

Part of the joy of listening to this ensemble in concert is the music that is presented. The choir’s music spans centuries and several musical styles, an eclectic and ecumenical mix, and all is sung with conviction. St. Olaf is a Lutheran Church-related college, so the choir’s repertoire consists almost entirely of sacred music. Some of this music is familiar, such as a three-section “Singet dem Herr nein neues Lied” by Bach, or Palestrina’s “Sicut Cervus,” which in English is the familiar text, “Like As a Hart Desireth.” Some is not familiar, such as Rene Clausen’s new and unpublished “Ave Rosa,” which contains some amazing choral suspensions, or Ralph Johnson’s recently composed “On Horizon’s Brim,” with its tricky cadences.

One would be hard pressed to pick a favorite or two out of the Raleigh program, so well performed was the music from start to finish. The singers provided a stunning a cappella reading of Mendelssohn’s “For God Commanded Angels To Watch Over You” and a lovely setting of “Blessed Are the Pure of Heart” by the 19th century Moravian composer Woldemar Voullaire, sung in German and accompanied by a small chamber ensemble. The choir paid homage to its own roots with “Light Everlasting” by Olaf C. Christianson, the second conductor of the choir, and, to close the program, the equally lovely arrangement of “Beautiful Savior” by F. Melius Christiansen, the first director. (Many would be familiar with the latter as “Fairest Lord Jesus,” set to the tune “St. Elizabeth.”) Also notable were the lively version of the 23rd Psalm from the 17th century Scottish Psalter, in which the men’s voices provided a nice bagpipe-sounding drone, and an English translation of Alexander Gretchaninoff’s “Our Father,” which featured a wide range of dynamics and especially fine singing by the tenors.

More modern music also was part of the program, including an energetic spiritual, “My Soul’s Been Anchored in the Lord” by Moses G. Hogan Jr., and the contemporary “Before I Go My Way” by Peter Hamlin, in which the choir was accompanied by violist Charles Gray from the St. Olaf music faculty. This was perhaps the least accessible piece on the program, although the chilling close harmonies at the beginning were notable, and the sustained chords at the end were quite nice. The two secular pieces on the program, James Erb’s well-known arrangement of “Shenandoah” and Alfred Paulsen’s marvelous “Norge, mitt Norge,” a Norwegian folk song sung in Norwegian, were outstanding.

The concert contained hardly any solos, but soprano Anna Shevik from White Bear Lake, Minnesota, sang with a warm and lovely tone in “Beautiful Savior” and Kenneth Leighton’s “A Hymn of the Nativity.” Soprano Kerry Auer from Savanna, Ga., had a brief solo in “On Horizon’s Brim,” and violinist Greta Bauer of Minneapolis had nice solo lines in that piece as well. Bass Andrew Bourgoin of Conway, Arkansas, also played a lovely piano accompaniment for “It Is Well With My Soul,” a beautiful if florid Victorian piece by Philip P. Bliss, as arranged by Yu-Shan Tsai.

The audience, which nearly filled the concert hall, contained many choral directors and choral singers, along with St. Olaf alumni, and one cannot imagine anyone leaving the concert with anything but the utmost admiration for the talents of this outstanding ensemble.