Singer and pianist Shirley Horn defies conventions as casually and reflexively as most of us cough–though of course she makes it sound a lot better than that. In the 70s, a decade not exactly known for producing restrained and tasteful jazz, she turned heads by nesting her whispery vocals within a relaxed, centered trio, which she led from the keyboard. And to this day she regularly commands concert audiences and festival crowds with a style better suited to some tiny boite. When she sings a ballad, she’ll downshift further than anyone since Betty Carter, then drag her phrasing behind this already glacial beat; it sometimes feels like you could step out for coffee between syllables. Even on material that would seem to demand more fire–such as the album of Ray Charles songs Horn recorded in 1993–she stays unruffled, creating a delicious tension between what she sings and how she sings it. And no matter what the tune or setting, she never fails to swing. It certainly helps that Horn continues to lead her own piano trio–she’d probably never find an accompanist so well attuned to the liberties she takes with tempo and phrasing. Her breathy timbre and knowing inflection brook few comparisons, and her sparse chords and patient improvisations carry their own fragile magic–she sings better than any good pianist since Nat Cole and plays with more authority than you’d expect from such an exquisite vocalist. Several tracks on her 2001 disc, You’re My Thrill (Verve), place her in front of small-orchestra arrangements by Johnny Mandel, but her voice makes those tunes feel as intimate as a session with her trio. It’s that group she brings to Chicago, on a double bill with the trio led by octogenarian pianist and radio host Marian McPartland. Friday, May 17, 8 PM, Orchestra Hall, Symphony Center, 220 S. Michigan; 312-294-3000 or 800-223-7114.

Art accompanying story in printed newspaper (not available in this archive): photo/Larry Busacca.