African music incorporates a wide variety of traditional instruments including idiophones like balafons, rattles, and drums; membranophones like talking drums; chordophones such as the kora harp; and aerophones including flutes, whistles and animal horns. Many African instruments are made from natural materials found in the environment like wood, gourds and animal skins. Vocal music often takes the form of call-and-response choral singing where a soloist or small group sings a line and the full chorus responds with a refrain.