Crash Ensemble, Ireland’s leading contemporary music group. (Ros Kavanagh)

I used to say that the soprano Dawn Upshaw was best at music that called for her to sing ethereally in a white dress, such as Olivier Messiaen’s “Saint-Francois d’Assise,” in which she played an angel, an otherworldly being making a pure and pretty sound.

On Tuesday night, I realized that it’s long past time for me to lose this idea, because Upshaw has developed into a very different kind of singer. No longer an innocent blond ingenue, she’s now an earth mother figure who explores all the in-between sounds of the voice and isn’t really interested in sounding like an opera singer at all.

Upshaw appeared with the Crash Ensemble, Ireland’s leading contemporary music group, and the bulk of the evening was two works by its founder and artistic director, the composer Donnacha Dennehy. But she opened the evening with a piece that’s so much her trademark it’s become a veritable sonic logo, something she sings at every concert, so you know it’s her: Golijov’s “Lua descolorida” (“Moon, colorless,” a poem by Rosalia de Castro). And to my ear, it became a statement of how far she’s come. Singing it with a string quartet, she emphasized not the soaring lines, but the fragmented phrases. You were aware of breath and the effort of channeling it into song, something she even (perhaps unconsciously) mimed with little pulling gestures of her hands. The song is a long plea for death; as she sang it, you could hear the suffering in the notes.

Although Upshaw was the marquee name on the program, she wasn’t its centerpiece. The show, presented by the Kennedy Center’s Fortas Chamber Music series, was actually a kind of belated album tour for a CD that came out in 2011, joining two works by a young Irish composer few had heard of, one of them — “That the Night Came,” a setting of six William Butler Yeats poems — written for Upshaw. The other, “Gra agus Bas” (“Love and Death”) was written for the traditional Celtic singer Iarla O’Lionaird, and represents a meeting-ground somewhere between art music and tradition. O’Lionaird performed with an assistant at his side who appeared to be guiding him through the score, presumably since his music is not usually notated.

I already enthused about this recording when it appeared, and was happy to reencounter it, although the shock of discovery of this inventive, uncategorizable, energetic music had ebbed, in the intervening years, in part because the idiom — smart genre-defying chamber ensembles with electric guitars — has been expanding steadily for some time. Not that this score falls into any known category: It explores the primal aspects of folk music in a range of methods, from straight-ahead percussion beats to just playing intonation to create a kind of suspended dreamscape of sound around the coiling keening of O’Lionaird’s voice.

The gifted conductor Alan Pierson, in stocking feet as if to emphasize his own connection to the earth (he had forgotten his shoes, but prefers to conduct barefoot in any case), kept the playing vivid in both this and the more conventional “That the Night Came,” which illustrates Yeats’s texts in ways at once literal and utterly fresh (for instance, the instrumental evocation of weariness in “The White Birds,” where the music sags briefly in dragging exhaustion before Upshaw enters to put words to the mood).

Upshaw’s work in Golijov’s folkish song cycle “Ayre” demonstrated the kinds of edge and sound effect she can bring to music. This cycle didn’t call for such a wide range, but its possibility was present. There are more interesting things to do with a voice, in Upshaw’s world, than simply emit clear, pure vowels, and in finding partners such as Dennehy, she’s expanding the canon while she does it.