For their early winter public concert, the East Carolina University Chamber Singers successfully negotiated an incredibly difficult program of 20th century choral works, highlighted by Frank Martin’s Mass for Double Chorus. They also sang shorter works by Elliott Carter and Samuel Barber, and as if one hefty composition weren’t enough, they sang Benjamin Britten’s challenging “Hymn to St. Cecilia.”

All a cappella, all the time.

The concert, before a large and appreciative audience at St. Paul’s Episcopal Church, again showed the considerable vocal skills, technical excellence and musical artistry of the nearly 50 best singers on the ECU campus, not to mention the splendid direction given the group by Dr. Daniel Bara, director of choral activities, who each year presents performance and repertoire standards that might prove too much for lesser ensembles.

The singers opened the program with Charles Wood’s stirring “Hail Gladdening Light,” singing in two groups antiphonally from the outside aisles of the church. The short piece offers each vocal section a chance to shine in a choral setting, and the basses were especially noteworthy on the line “We hymn the Father, Son, and Holy Spirit divine,” while a lovely soprano line, “Therefore in all the world thy glories, Lord, they own,” brought the piece to a close.

The Carter piece, set to Emily Dickinson’s poem “Musicians Wrestle Everywhere,” was surprisingly accessible as it matched quirky music to quirky lyrics. At times, the music resembled more of a choral composition exercise, but there were some nice harmonies. Two of Barber’s Reincarnations for a cappella chorus, Op. 16, “Mary Hynes” and “The Coolin (The Fair Haired One),” offered a nice contrast in sound. The former was a sprightly piece that required pretty nimble work by the singers; the latter was more relaxed, marked by parts that soared with beautiful harmonies.

The singers closed with William Harris’ beautiful “Faire Is the Heaven,” a staple of the Anglican choral repertoire, and to say that the Choral Singers did it justice would be an understatement. The suspensions were breathtaking, and the soprano lines soared. And the singing was just as beautiful at the end of a concert of demanding works as that on the Wood piece that opened the program.

In between the Wood and Harris selections, the Britten and Martin works made up the heart of the program. Either could have been the single focal point of an ordinary group’s concert, but the ECU ensemble handled both with considerable skill.

Britten’s “Hymn to St. Cecilia,” set to a text by W.H. Auden, is marked by unusual (and sometimes unexpected) harmonies and key changes and tricky rhythms. In one section of the opening “In a garden shady,” for example, the men’s lines are sung in a slow cadence while the women’s lines are sung in almost a lilting three-quarter time. The second “I cannot grow” section sounded almost as if three or four different time signatures were being sung simultaneously. Soprano Erin O’Leary had a lovely solo in the third section (“O dear white children”), as did alto Katy Avery in the same section (“O weep, child, weep”). Nathan Walker and Harris Ipock also had good solos in the final section (“That what has been may never be again” and “O wear your tribulation like a rose”).

The Martin mass, written in the 1920s, is a large-scale piece marked by some gorgeous lines, but it also contains some hazards that could cause a musical train wreck if not well-rehearsed and executed with precision. The singers are required to sustain pitches for considerable time (as in the opening Kyrie, for example), and the score also has distinct and sometimes sudden dynamic changes, tricky suspensions and sharp entrances and cutoffs. Like the Britten piece, the Martin mass has some sections of unusual rhythm.

The Chamber Singers sang with confidence, and as they have shown in previous concerts, they possess a vocal maturity that is striking — even as some graduate and new members take their places. These are well-trained singers, and the highest highs are never shrill or thin, and the lowest lows are never muffled into tunelessness. Moving passages flow beautifully, as in the “Crucifixus” passage of the Credo section, and the blend of four (or more) parts is a velvet seamless sound that one hears in the most professional of choral ensembles. Some voices do stand out, but not at the expense of the group. Bara has some sopranos, for instance, whose pitch and clarity are thrilling to hear, and the bass section provides great musical weight, as in the entire Credo section, and not just a rumbling sound.

Martin’s mass is contemplative, original, often strikingly beautiful, and the Chamber Singers gave a polished performance that adds even more luster to their already glowing reputation. The Chamber Singers plan to perform part of the mass at the regional meeting of the American Choral Directors Association in Memphis in March, and a broader audience will be able to experience the excellence that eastern North Carolina audiences have come to expect at every local performance.