A singing style that features a leader who is imitated by a group is called?

A singing style that features a leader who is imitated by a group is called "call and response." In this musical form, the leader (or caller) sings a phrase, and the group (or responders) echoes or replies with a corresponding phrase. This technique is commonly found in various musical traditions, including African, gospel, and Folk Music, fostering participation and interaction among singers.