As the powerful singing voice of 71-year-old Liu Aibang echoes across the classroom, students manipulate shadow puppets with rods, making them step onto the "stage" -- a translucent cloth screen illuminated from behind.

Those sitting in front of the stage play music on gongs, drums, suona horns and other instruments.

This is a Daoqing shadow puppetry class at Longdong University in Northwest China's Gansu province. Aside from Liu, the 30-plus performers of the show are all college students with an average age of around 20.

Originating in the Han Dynasty (202 BC-220 AD), Daoqing shadow puppetry in Gansu is an important branch of Chinese shadow puppetry and has been included in the national intangible cultural heritage list since 2006.

LOSING ITS SHINE

Hailing from Huanxian county, the hometown of Daoqing shadow plays, Liu has been performing shadow puppetry for 57 years. The farmer began learning the craft from his father when he was 14. Over the past decades, he has mastered special techniques such as folk singing and the ability to play various musical instruments.

For years, shadow plays were welcomed by audiences of all ages in rural China, and were staged for every major occasion. However, with films and television series gradually becoming major sources of entertainment in the late 1980s, the art's popularity waned and many performers moved on to other jobs.

As more young people left the villages, Liu faced the problem of finding people to whom he could pass the tradition, an issue faced by other guardians of heritage.

"I missed those days when people didn't have smart phones, iPads or computers, and we were crowded with audiences during the whole show," Liu said.

Faced with the choice between protecting this artistic heritage and making a decent living, he chose to stay on, continually improving his techniques to shoulder the entire troupe's work alone.