No one has answered this challenge more adroitly than Ladysmith Black Mambazo, the South African male a cappella group that mostly sings in Zulu. Since its collaboration with Paul Simon on "Graceland" introduced it to American audiences, the group has recorded a Broadway musical, a children's album and a gospel album. It also has contributed to numerous soundtracks and has collaborated with everyone from George Clinton to Dolly Parton. On its latest album, "No Boundaries," Ladysmith Black Mambazo works with the English Chamber Orchestra strings to fuse South African folk music with European art music.

The South African-born, Germany-based pianist Isak Roux wrote the arrangements for the widely varying material -- "Amazing Grace"; hymns by Bach, Mozart and Schubert; "Homeless" from "Graceland"; Roux's new music for "Dona Nobis Pacem"; an old Ladysmith song; and traditional Zulu numbers. The 10 singers are backed by 13 strings, five horns, three percussionists, harp and Roux.

There are many ways this collaboration could have gone horribly wrong, but Roux and Ladysmith leader Joseph Shabalala negotiate every danger. The orchestrations are quite restrained, adding color to the vocal harmonies without overwhelming them, and the strings play percussively enough to fit the Zulu rhythms. The singers use their well-honed precision to fit the arrangements without losing their township flair, and they give listeners one more reason to buy a Ladysmith album.

-- Geoffrey Himes