The structure of "Song Ben" explains a complete story in the way that performers sing a variety of roles themselves. The development of Big Ben is relatively mature in music and performing arts, forming a complete sound cavity system, which is called "three cavities, nine boards and eighteen tunes". Three schools: three-cavity general guide cavity, northern cavity and Haidong cavity; Nanqiang music has nine boards and eighteen tones, which are euphemistic and soft; North cavity and nine boards; Thirteen-cavity, high-pitched and thick. Jiuban is a qupai used to express various emotions such as joy, anger, sadness, joy, shock, fear and resentment, such as high cavity, crisp board, positive board, flat board, small crying board, crying board, yin and yang board, side board and punching board. Eighteen tunes are minor tunes interspersed with emotions, such as memorial tune, sparrow tune, flower spectrum tune, Taoist sentiment, herding sheep tune, flower tune, yin-yang tune and so on.