Like so many other "American Idol" finalists, Kimberley Locke is struggling to find a niche. On Monday night at the Birchmere, she performed tracks from her debut album and a slew of covers, including songs from her turn on the second season of "Idol" (a jazzy version of "Somewhere Over the Rainbow") and favorites from her youth (Chaka Khan's "Through the Fire").

Although her selection of covers was personal -- Locke introduced each one with a story about its meaning to her -- the songs were not always well suited to her voice. She sounded hoarse at the top of her range, which threw her slightly off-key in songs such as Whitney Houston's "Where Do Broken Hearts Go." However, Locke recovered with the ballad "Before," which was pitch-perfect even in the depths of her lower register.

Locke's biggest weakness was her backing band. In Stevie Wonder's "Do I Do," she could barely muster any soul over the blandness of the white-bread quartet, which she introduced as the Blue-Eyed Boys. It was no surprise to learn that this was only the band's second show together: The guitarist and bassist stared at their music stands, making the evening feel more like a practice session than a polished concert.

Openers Oktbrwrld more than made up for what Locke lacked in soul. Despite being seated, the acoustic foursome drove their songs forward with nontraditional percussion (such as rhythmically slapping the body of a guitar) and simple, well-arranged melodies. Their passion shone through on a long a cappella jam, anchored by unwavering vocal percussion, that spotlighted the harmonies of the group's two female singers.

-- Catherine P. Lewis