For classical-music listeners thirsting for summer concerts, the Church of the Epiphany offers a weekly oasis. The most recent concert in its free Tuesday noontime series featured rarely heard medieval music, mostly in Old French, performed by the local ensemble Armonia Nova. Even though all of the details were not in place, it was a welcome chance to hear music more than six centuries old.

With just three performers — two singers accompanied by a harpist, Artistic Director Constance Whiteside — the sound was delicate and pretty, easily heard in the Washington church’s resonant acoustics. Countertenor Corey McKnight had a clean, mostly unstrained sound, particularly fine in the rondeau “Je me demande ma bienvenue” by Johannes Haucourt — the tone perhaps just slightly pinched at the top. He seemed the more securely prepared of the singers, with soprano Nancy MacArthur Smith getting off to a false start in “En non Diu/Quant voi,” a Notre Dame motet from the Montpellier Codex. She was perhaps not sure of her starting note but got back on track.

Whiteside played one solo dance piece, a 13th-century estampie, which was a little cautious in terms of tempo and vigor but pleasant enough. The program’s highlight, two ballades by Guillaume de Machaut, one of the great composers of any period, featured the voices in intricately entwined lines, although both seemed to push MacArthur Smith to the upper edge of her comfort level. She was at her best in solo outings, on the top line of Machaut’s virelai “Moult sui de bonne heure nee” and the Montpellier motet “Biaus douz amis.”

Downey is a freelance writer.