A decades-long friendship between Minnesota Orchestra principal flute Adam Kuenzel and Venezuela-born composer Manuel Sosa led to the commission of "Eloquentia" ("Eloquence") for Flute and Orchestra, heard in its world premiere at Orchestra Hall on Thursday night.

Sosa proved a challenging friend, demanding many radical sounds from the soloist, from tongue vibrato, to vocalizing through the tube, where the sound is of breath rather than notes, to multiphonics, sounding multiple notes simultaneously.

For all the extreme effects, Sosa is unlike the abstract, intellectual composers who dominated classical music in the latter half of the 20th century. He seeks to make an emotional connection with the audience. The work has a clear and satisfying arc.

In the opening, the flute is restrained, as if lurking in the shadows. It then takes off in a ferocious cadenza, as if at war with the orchestra. In the end, Sosa engenders a reconciliation between the forces, creating a cathartic release.

Kuenzel's playing may not have been traditionally beautiful, but he met the work's formidable demands in an intense partnership with music director Osmo Vänskä and the orchestra.

Duruflé's Requiem takes Gregorian chant and refracts it through the prism of French Impressionism. Like his contemporary, Fauré, Duruflé omits the most dramatic section, the Dies irae ("Day of Wrath"), creating a work of sublime serenity.

Vänskä pushed the gentle work overly hard. The "Hosannas" in the Sanctus were less joyous than hysterical. And in the climaxes, the orchestra sounded ragged and under-rehearsed.

In the quieter moments, Vanska was more successful. The "Pié Jesu" ("Merciful Jesus") was stunning. The women's voices, accompanied by the lower strings, created a genuine sense of peace and rest.

In past seasons, the orchestra would have partnered with Minnesota Chorale. The substitution of the St. Olaf Choir was significant. Their comparative lack of maturity and experience showed. There was a degree of full-bodied sound that was missing, not to mention intonation problems. Vänskä was forever gesturing the chorus to sing up to the pitch.

The concert opened with an energetic performance of Stravinsky's Concerto in D major. Modeled after Vivaldi's concerti grossi and scored for string orchestra, it showed off individual members of the section.

William Randall Beard writes regularly about music.