"Whenever I research a music form, I wish to find such locales where the traditions are still thriving," Mu says.

"In Yandong, a lot of people are still singing Grand Songs. It means that the tradition is still very vibrant there. It exists as more than just an intangible cultural heritage, but as an integral part of people's lives."

He spent four days in Yandong, where he met and befriended many local singers, chatting with them while observing their daily antiphonal performances at the drum tower. It was on this trip that he first recorded some of their singing.

"The Grand Song is an orally transmitted polyphonic type of music. The singers are able to master intricate harmonies without the need of a musical score, with bright female voices contrasting with resonant male voices. It stands out as one of the world's distinctive musical forms," he says.

"It is so closely connected with the lives of the Dong people. A lot of their singing techniques are derived from imitating sounds of the natural world, which can provide inspiration for philosophical thoughts originating from music."

In a bid to enable more people to learn about this unique musical tradition, he recommended the Yandong choir to the World Music Shanghai Festival in 2013, where four concerts were staged across the city.