 Liberian music makes particular use of vocal harmony, repetition and call-and-response song structure as well as such typical West African elements as ululation and the polyrhythm typical of rhythm in Sub-Saharan Africa.Christian music was introduced to Liberia by American missionaries and Christian songs are now sung in a style that mixes American harmonies with West African language, rhythm and the call-and-response format.Traditional music is performed at weddings, naming ceremonies, royal events and other special occasions, as well as ordinary children's songs, work songs and lullabies.