Classical vocal music can be a hard sell, but a capella groups specializing in early music, for whatever reason, are not. Think Anonymous 4, the Kings Singers or the monks who occasionally land CDs called “Chant” on the pop charts. I suspect one reason is that these ensembles are balanced on the audience-friendly line between spirituality and easy listening: Their music is genuine and sincere but doesn’t involve too much hard work for the audience.

Trio Mediaeval strides this line with grace and integrity. The three Scandinavian women have been singing together since 1997. Every group has a gimmick; theirs is, most obviously, the easy amalgamation of contemporary composers and music long dead. They treat the historical works they perform not as canonical texts but as a tradition they are free to interpret and play with.

Historically, this tradition generally excluded women, which gives a subversive twist to contemporary women’s embrace of it. “A Worcester Ladymass,” Trio Mediaeval’s newest album, isn’t the first example of women taking on music that was written to honor the Virgin Mary — a wildly popular object of veneration in pre-Protestant England — and shifting its focus slightly by singing it themselves. Anonymous 4, for instance, released “An English Ladymass” as long ago as 1993. Nuns also performed Lady Masses, but the scraps of music assembled for Trio Mediaeval’s current project came from a 13th-century Benedictine monastery and were sung by men.

And even nuns probably didn’t cultivate the feminine warmth that Trio Mediaeval offers in lieu of the sexless purity generally associated with this repertory. There’s no question that these are living women singing, with expressive feelings, including a hint of mischievous delight at the start of the Gloria, and a tear-laden “Cruxifixus etiam” in the Credo.

This performance is an act of recontextualization, as Anna Maria Friman, the group’s Swedish soprano, points out in the CD’s brief liner notes. Offering a spirituality stripped of most of its specific religious associations (the Latin texts are even printed in the booklet without translation), the album lightly raises the question of how to honor women in an entirely different society.

But if there’s an agenda, it’s incorporated organically into the music — as is the interpolation of two contemporary segments among the medieval works. The British composer Gavin Bryars, using the same tools and the same musical vocabulary as the original music, created a Credo and a fleeting Benedicamus Domino that neither try to masquerade as old nor assert themselves as defiantly new. They simply take their place among the other expressions of praise, the Credo as the work’s musical heart, the Benedicamus as a fleeting coda returning the listener to the world of today.

A Worcester Ladymass

ECM New Series 2166