Kaija Saariaho's "Voix, Espace" at Zankel Hall In an onstage interview at her Making Music concert at Zankel Hall on Monday evening, the Finnish composer Kaija Saariaho explained her approach to "From the Grammar of Dreams," a 2007 setting of Sylvia Plath texts, by making a fascinating distinction between wakefulness and dreaming. When you are awake, she told Jeremy Geffen, the moderator, you speak in sentences that move sequentially through time. But when you dream, your speech can be four-dimensional. Voix, Espace The vocal ensemble Solistes XXI performed five compositions by Kaija Saariaho on Monday at Zankel Hall, accompanied by multimedia installations by Jean-Baptiste Barrière. It may be hard to prove that assertion. But it tells you a lot about why Ms. Saariaho, who holds the Richard and Barbara Debs Composer's Chair at Carnegie Hall this season, writes such arresting, otherworldly music, and why the five works for voice and electronics that she presented were so thoroughly entrancing. The program, "Voix, Espace," is a collaboration between the composer, the French vocal ensemble Solistes XXI and Jean-Baptiste Barrière, a French video artist who has produced visual imagery for many of Ms. Saariaho's works in recent years. As multimedia collaborations go, it was unusually well balanced. Ms. Saariaho makes varied use of electronics, sometimes simply altering vocal timbres or cloaking them in dense reverberation, elsewhere adding layers of bell-like percussion, whispers or recorded voices. Her approach is never heavy-handed or overwhelming: the live voices and the electronics seem interwoven, almost organic. So does her text setting, which closely follows the spirit, if not every gesture, of the poetry at hand, just as Mr. Barrière's video mirrors the timbres, shapes and imagery of Ms. Saariaho's music. In "Lonh" ("From Afar," 1996), a solo soprano work given a virtuosic reading by Raphaële Kennedy, 12th-century poetry by Jaufré Rudel is rendered in a melismatic style that oscillates between neo-medievalism and modernist abstraction. Mr. Barrière's visual backdrop mixes morphing cloudscapes with antique woodcuts. "From the Grammar of Dreams" (1988), originally a duet for soprano and mezzo-soprano, was heard in a solo soprano version, in an evocative performance by Maryseult Wieczorek. It draws on two Plath works: a poem, "Paralytic," and a section from the novel "The Bell Jar." The texts are often set against each other, one sung live, the other as a ghostly electronic counterpart, as if the singer were in a distressed dream world, expressing contrasting ideas simultaneously. In Mr. Barrière's visual counterpart, clouds and ocean waves melt into one another and begin to resemble Rorschach test shapes, and live video of Ms. Wieczorek, shown in two versions - clear and distorted - fades in and out of the picture. Though the solo works were especially transfixing, the program's ensemble pieces - "Écho!" (2007) and "Tag des Jahrs" ("The Time of the Year," 2001), for eight voices, and "Nuits, adieux" ("Nights, Farewells," 1991, revised in 2007), for four - were richly contrapuntal and couched in shifting colors. They showed the considerable collective flexibility of Solistes XXI (which also sings early music) and its director, Rachid Safir, who conducted from the foot of the stage. Kaija Saariaho and the cellist Anssi Karttunen will conduct sessions of a Professional Training Workshop at Weill Recital Hall on Friday and at Zankel Hall on Monday. On Saturday the St. Louis Symphony Orchestra and the soprano Karita Mattila will perform Ms. Saariaho's "Quatre Instants" at Carnegie Hall; (212) 247-7800, carnegiehall.org.