Joseph Shabalala, the gentle-voiced South African songwriter whose choir, Ladysmith Black Mambazo, brought Zulu music to listeners worldwide, died on Tuesday in a hospital in Pretoria. He was 78.

The cause was not immediately known, but his health had deteriorated after he had back surgery in 2013, said the group’s manager, Xolani Majozi, who announced the death.

Mr. Shabalala began leading choral groups at the end of the 1950s. By the early ’70s his Ladysmith Black Mambazo — in Zulu, “the black ax of Ladysmith,” a town in KwaZulu-Natal Province — had become one of South Africa’s most popular groups, singing about love, Zulu folklore, rural childhood memories, moral admonitions and Christian faith.

Ladysmith Black Mambazo’s collaborations with Paul Simon on his 1986 album “Graceland,” on the tracks “Homeless” and “Diamonds on the Soles of Her Shoes,” introduced South African choral music to an international pop audience.