Pansori is an epic narrative song form unique to Korean music culture. Musicologists do not necessarily agree on the origin of the music form but one recent theory suggests that it developed out of Korea's story-telling tradition, that story-tellers gradually began to include musical elements to make their performances more captivating for the audience. The development of pansori was strongly influenced by shaman rituals as illustrated by common elements which exist in both music forms. The vocalist alternates between speaking and singing as the story progresses and uses a fan and a handkerchief to help illustrate the various scenes of the story. The speaking sections are referred to as aniri, the singing as sori, and the actions as ballim. The barrel drum player or members of the audience can call out words of agreement or encouragement throughout the performance and these vocal exhortations are called chuimsae. Pansori was popular in the 18th and 19th centuries and documents show us that there were originally 12 works but today only 5 works remain in performance practice. These works are performed entirely by a single vocalist accompanied by a barrel drum which is rather challenging as full performances can last up to 8 hours in some cases. The text of four of the remaining works are traditional Korean stories while the fith work is based on a traditional Chinese story. The 5 remaining works of pansori are: Song of Chunhyang, Song of Shimchong, Song of Heungbo, The Underwater Kingdom, and Song at Red Cliff.