Inscribed in 2009 (4.COM) on the List of Intangible Cultural Heritage in Need of Urgent SafeguardingCa trù is a complex form of sung poetry found in the north of Viet Nam using lyrics written in traditional Vietnamese poetic forms. Ca trù groups comprise three performers: a female singer who uses breathing techniques and vibrato to create unique ornamented sounds, while playing the clappers or striking a wooden box, and two instrumentalists who produce the deep tone of a three-stringed lute and the strong sounds of a praise drum. Some Ca trù performances also include dance. The varied forms of Ca trù fulfill different social purposes, including worship singing, singing for entertainment, singing in royal palaces and competitive singing. Ca trù has fifty-six different musical forms or melodies, each of which is called thể cách. Folk artists transmit the music and poems that comprise Ca trù pieces by oral and technical transmission, formerly, within their family line, but now to any who wish to learn. Ongoing wars and insufficient awareness caused Ca trù to fall into disuse during the twentieth century. Although the artists have made great efforts to transmit the old repertoire to younger generations, Ca trù is still under threat of being lost due to the diminishing number and age of practitioners.