Scott Metcalfe can recall the first concert by the group then known as Blue Heron Renaissance Choir. It was Oct. 16, 1999, at Saint Peter’s Episcopal Church in Cambridge. On the program were selections from the Peterhouse partbooks, a treasure trove of pre-Reformation polyphonic vocal music that at the time was virtually unknown. A small audience listened as Metcalfe led an ensemble of singers through intricate works that were both hundreds of years old and completely unknown to those hearing them.
“I remember there weren’t a lot of people there, typical for a launch concert for a new group,” he said in a recent interview. “But I [also] remember the music being really intense, and just feeling, wow, we’ve got all this possibility for this amazing new ensemble.”
Just how much potential there was became clear over the ensuing 20 years. From that humble start, Blue Heron — which Metcalfe founded with singers Cheryl Ryder and Nöel Bisson to sing music of the early 14th to the late 16th centuries — has long since made itself an indispensable part of Boston’s musical ecosphere. (The group dropped the “Renaissance Choir” part of its name several years ago.)
The strands that make up Blue Heron’s artistic DNA include, first and foremost, the meticulous care with which the group prepares its repertoire. There is also its drive to unearth and feature long-buried masterpieces (“early music as new music,” as the group’s website puts it). And there is its vocal style, which emphasizes passion, directness, and character over a more ethereal, blended sound.
“I’m not interested in homogenizing things,” Metcalfe said. “What I really like, and I think this is straight out of the music, is that every line in the music has its own identity. You actually don’t want people to blend; you want to hear individual voices.”
Part of what makes this sort of precise artistry possible is a scholarly approach to rehearsal honed through two decades of shared experience coping with the formidable demands of this repertoire. While Blue Heron’s membership has, inevitably, changed over time, Metcalfe noted that its “core” membership (around a dozen singers) has proven relatively durable. Baritone Paul Guttry has been with the group since its first performance, tenor Mark Sprinkle since its second set of concerts.
“The level of ensemble we can achieve in any given concert is not just the product of the rehearsals that week; it’s the product of rehearsals for years,” Metcalfe explained. “There’s a whole suite of technical skills that we have as a group because of that experience together. Things about historical pronunciation, of the way the tuning systems that we use are not what are used today. And we’ve had to learn how to do that and apply it. You can’t do that in a week.”
Another facet of Blue Heron’s activity is Metcalfe’s desire to tackle large-scale projects over multiple seasons. Chief among these is the Peterhouse series, a musical immersion that has produced an outstanding five-CD set of recordings. (Metcalfe mentioned that he wants to do at least a couple more, depending on funding.) Another example is its “Ockeghem@600 ” project, for which the group plans to have performed the complete works of the Franco-Flemish composer Johannes Ockeghem by 2021, the approximate 600th anniversary of his birth.
Part of the motivation behind these deep-dive endeavors is the fact that Blue Heron trades regularly in obscure repertoire for which there’s often no existing performance practice to guide the group’s approach. Especially with music like Ockeghem’s, he said, they are creating that tradition themselves.
A swath of upcoming concerts offers glimpses of the diversity of the group’s work. On Wednesday, they perform a program of 14th-century song at Brandeis University as part of a two-day workshop. Two concerts in the Seaport district follow: Italian madrigals by the Franco-Flemish composer Cipriano de Rore (a recording of which has just been released) next Friday, and a 15th-century program next Saturday. Next Sunday brings a performance in the Pindrop Sessions at Aeronaut Brewing Company in Somerville: for the occasion, Somerville Mayor Joseph Curtatone will recite some of the Italian poems set by Cipriano, and Aeronaut will brew a special beer using yeast from a Belgian town near Ockeghem’s birthplace.
Like any musical group that exists at the margins of popular culture, Blue Heron faces a continual struggle to survive and grow. While he touts the involvement of the group’s board and the support of “a broad donor base,” Metcalfe acknowledged that “it’s very difficult to keep body and soul together doing this. We’re not in a real comfortable position.” Nevertheless, he speaks with an almost childlike wonder at how far the ensemble has come, and the difference in how the group and its no longer so obscure repertoire are now received.
“We can do a concert of music that no one in the audience has heard a note of,” he said, “and there’s 350 people in the audience when we walk out at First Church [in Cambridge]” where the group’s main concert series is held. “And every time we do that, I’m floored. It never ceases to amaze me that we can do this and people show up.”
At Brandeis University, Waltham, Oct. 30; District Hall, Nov. 1; Our Lady of Good Voyage, Nov. 2; Aeronaut Brewing Company, Somerville, Nov. 3. www.blueheron.org