Originally an a cappella quintet that mixed African polyphony, medieval chant and jazz vocalese, Zap Mama has continually sought new musics to assimilate. The Brussels-based group's new "A Ma Zone," its fourth U.S. release, includes contributions from Philadelphia hip-hoppers the Roots and Cameroonian saxophonist-singer Manu Dibango, as well as drum'n'bass beats on a few songs that indicate Zap Mama founder Marie Daulne has been listening to Bjork. Still, this disc is not as frantically eclectic as the ensemble's last outing, "Seven."

Actual drums and bass -- and touch-tone bleeps on the Bjorkian "Call Waiting" -- now underpin the group's sound, but this album shifts the emphasis back toward interwoven female voices. The disc's hip-hop moves add little more than yet another call of "check it out," but such traditional Zap Mama material as "Gissie," "W'Happy Mama" and " 'Allo 'Allo" remains appealing. The lilting, exuberant vocals of these tracks suggest that Daulne needn't try so hard to discover new stylistic voices.

Appearing Saturday at the University of Maryland's Inn and Conference Center. To hear a free Sound Bite from Zap Mama, call Post-Haste at 202/334-9000 and press 8114. (Prince William residents, call 690-4110.)