Like many of his albums, Harmony had its birth with one of guitarist Bill Frisell’s flickering thoughts. It might be fun, he mused, to make music with a cellist, a vocalist and a baritone guitarist. (Hank Roberts, Petra Haden and Luke Bergman— musicians he’d worked with individually, but never as a group— filled those roles, respectively.) One of the most adaptable and prolific musicians alive, with the support of a grant from the FreshGrass Music Festival, Frisell first performed the music that would lead to his latest album in a live setting in 2016. Harmony , which doubles as the name of the band and marks his debut for Blue Note, found its tone and direction when Frisell realized that Roberts and Bergman also sang, and that the three band members’ voices blended in a particularly charming, precise and radiant way: That vocal fusion is as integral to the Harmony experience as Frisell’s low-key guitar work and the unusual accompaniment. Eight of Harmony ’s 14 tracks are Frisell originals, a rarity these days on his albums, and his compositions are deliberately spare and direct; this is not the time nor place for experimentation or showboating. Haden’s lead vocals, on numbers like Frisell’s “Lonesome” and the lighter-than-air “Honest Man,” and on Pete Seeger’s folk staple “Where Have All the Flowers Gone?,” are often wraithlike and ephemeral. But the truly shiny moments come when the three voices, entangled with Frisell’s ever-perceptive guitar, become one rapturous, embraceable sound, as on the cover of the show tune “On the Street Where You Live” and Frisell’s “God’s Wing’d Horse.” Another highlight: the traditional cowboy song “Red River Valley,” which features three a cappella voices and no guitar at all, Frisell undoubtedly sitting in the room doing nothing but grinning.