A memorable recital from affable Upshaw

In a way, that is Upshaw in a nutshell. She is, indisputably, a great singer, with a voice that radiates power and unforced warmth. But her secret weapon is a casual, unpretentious demeanor that lessens the distance between stage and audience. Listeners in her presence experience music not as the inaccessible product of a holy art but as a thing of open, approachable beauty.

It's also what allows Upshaw to inhabit the character of her songs so effectively, as she did in both the Ives and a set of French songs. In Ives's "Memories" she turned on a dime from comic glee to wistfulness, and "Tom Sails Away" evoked the sad memory of a soldier leaving home for war. Debussy's "La chevelure" ("The Hair") teemed with a palpably erotic sense of longing, and in Messiaen's "Prière exaucée" ("Answered Prayer") the music exploded with primal fervor. She even served as page turner for Kalish as he gave a rhapsodic account of the "Alcotts" movement from Ives's "Concord Sonata."

The second half offered less consistent pleasures, though it began with an exquisite reading of Osvaldo Golijov's "Lua Descolorida." Most of it was given over to the Boston premiere of "Treny (Laments)" by Michael Ward-Bergeman, a commission of the Terezin Chamber Music Foundation. A setting of a 16th-century Polish poem by Jan Kochanowski mourning the death of his daughter, it adds flute, cello, and Ward-Bergeman's own hyper-accordion.

Darkness is everywhere in "Treny," which moves from simple melodies to dense, unsettling chords, and the accordion adds unusual sonic color throughout. The piece seems too long, diluting its effect, but it has poignant moments, especially when Upshaw hummed wordlessly into the resonant folds of Ward-Bergeman's instrument.

Three songs by William Bolcom closed out the main program, each drawing from popular American song traditions. "Waitin' " had a soulful gospel flavor, and "Amor," a gleeful cabaret song, found Upshaw perfectly balanced between art and entertainment. Audience members were unwilling to let her go, and she offered two encores: Bolcom's "George" and Schubert's "Im Frühling."