Leni Stern WHEN EVENING FALLS (Lenistern.com)

Leni Stern’s evolution from jazz guitarist began after she’d recorded nine instrumental albums. With this CD, her fourth as a singer-songwriter, Stern’s transformation seems complete. As you might expect, she has a wider sonic palette than most performers who fall into that category, drawing on the colors of horns and rich harmonic textures as well as gentle loops and samples in the vein of her one-time guitar teacher Bill Frisell. But what makes her numbers intriguing is the way she weaves the same graceful, unhurried sensibility that’s always colored her playing into her vocal performances and arrangements. Her tribute to Billie Holiday, "I’ll Be Seeing You," slips softly and slowly by like a summer day in its lyrics, as do the solos she incorporates into its bridge and finish.

Taking inspiration from her travels in Africa and New Orleans, Stern’s songs tap tribal folklore and rhythms and vocal passages heard in Nagaland melodies or from passing street vendors. In the closing "Abke Hum Bichere," she channels the sprits of the late qawwali singer Nusrat Fateh Ali Khan, with help from vocalist Dhanashree Padit Rai, and Django Reinhardt in an acoustic-guitar introduction that fuses Gypsy jazz and North African cadences. She still has a wicked way with a fretboard, yet every time she steps on a wah-wah pedal to spin a melody of shifting tones or lets loose a string of ringing, open notes, she beckons you deeper into the heart of her songs’ themes, whether that’s a celebration of groove like "Ice Cold Water $1" or the plea for liberation from one’s own dark side in "Dancin’ with the Devil."

(Leni Stern performs next Wednesday, July 14, at Scullers, in the DoubleTree Guest Suites Hotel, 400 Soldiers Field Road at the Mass Pike; call 617-562-4111.)