In August 2018, for example, He visited an 80-year-old man who lives nearby Yuyuantan Park in Beijing, who taught him to sing a folk song he sang as a child, titled Lugou Qiao, a famous place near the Wanping Fortress in Beijing's Fengtai district, often referred to as the Marco Polo Bridge. The song depicts the scenes of the camels traveling on the bridge which is adorned with hundreds of lion figurines.

"The song hit me. Though it is simple and short, I want to adapt it into a new song and let more people listen to it," He says, adding that his little daughter was the song's first listener.

To collect songs, he wakes up early in the morning and goes to local parks to meet elderly people, who are doing their morning exercises. He also carries his ruan (a traditional Chinese plucked stringed instrument). He invites the people in the park to play music with him. But building up trust can be a hit-and-miss affair.

"It's a process of looking for a needle in a haystack but it's interesting and worthwhile," he says. "Sometimes the elderly people are very interested in me and they tell me lots of stories, but sometimes they turn my requests down. It usually takes months to stay in one city to collect songs before we head to another city.

"What I am looking for is beyond music. I want to discover the connection between the songs and the listeners," He says.

His friend, singer-songwriter Sun Dasi, introduced He to his grandmother when he was in Shanghai to collect children's songs.

Sun's grandmother, Yang Junwen, who was born in Shanghai in 1930, sang the song, titled Row a Boat, to Sun when he was a child. She learned to sing the song when she was about 7 years old, and the song portrays the people who traveled to Shanghai by boat to make a living in the 1930s.

"My grandmother is very beautiful and independent. She had worked in a textile factory and took care of her three children," says Sun, who took He and a few other musician friends to visit his grandmother this June.

"When we sang the song together, she sang with us. Though she is 90 years old, she still remembers the song."