Two talented women -- one a vocalist, the other a singer-guitarist -- turn their rich musical imaginations to styles that flourished in the early to mid-20th century. Their tastes overlap at points, since blues and jazz color American music (if in widely varying tints), but their geographical and cultural references are not quite the same.

Introducing... revisits the sophisticated urban saloon music -- pop songs composed by jazz- and swing-influenced professionals -- comprising what's now called the Great American Songbook. The most celebrated living champion is Tony Bennett; nonliving masters include the likes of Bing Crosby, Billie Holiday, Frank Sinatra, Ella Fitzgerald and more. Sunny -- full name Sunny Crownover, originally of Texas, now of Massachusetts -- is so good at what she does that if this were the 1940s, everybody would know her.

Besides her expressive voice and magnificent interpretative skills, Crownover has the good fortune to be allied with producer and guitarist Duke Robillard, who's assembled a stellar acoustic quartet, including himself, fellow guitarist Paul Kolisnikow, bassist Jesse Williams and clarinetist Billy Novick. Sunny & Her Joy Boys perform 14 songs in stripped-down arrangements in which both voice and instruments have room to breathe. Listeners, on the other hand, will have their breaths taken away.

Unlike Crownover, Mary Flower is rooted in the soil of the rural/small-town South: country blues, ragtime, gospel and trad jazz, filtered through the folk revival of more recent history. You could think of her broadly as a female Leon Redbone, except that Redbone's singing is as defined by jazz as Sunny Crownover's. Flower's voice, which is not what one expects when one hears this kind of material (or some of it anyway), sounds like ... well, a voice, as opposed to a horn.

Not that there has to be anything wrong with that, of course. It's a perfectly respectable voice, perhaps most effectively employed in non-ragtime-blues songs such as the lovely "Portland Town," a Flower original not to be confused with Derroll Adams's anti-war ballad covered by Ramblin' Jack Elliott, the Kingston Trio and others in the 1960s.

What makes Flower and Bridges outstanding, though, is the exemplary acoustic-guitar picking. Influenced by the likes of Blind Blake and the Rev. Gary Davis on one end and John Fahey on the other, folk-blues circuit veteran Flower plays with passion and precision and creates power and beauty in just about anything those chords touch. Emmett Miller's "The Ghost of the St. Louis Blues," done with a small horn-and-piano group, manages to be both joyful and spooky. The solo original "Columbia River Rag" is the sort of perfectly realized creation that, wherever you are or whatever you're doing when it fills your ears, will carry you with it.