Four members of the vocal group Suiyuan Old Boys in Hangzhou, Zhejiang province.[Photo provided to China Daily]

Lou Yilin, Wang Zhecheng's wife, has become the group's director. "We figured out that the four members are fluent in English. But none of them have received any professional training in singing," she said.

Lou said the group has decided to work more on costumes and makeup to improve their impact on stage. They wear masks on stage, but remove them while giving their names after each performance. So far, they have staged six live performances.

Wang Zhecheng said the reason the group initially won so much attention is because of the country's aging problem, not necessarily the quality of their performances.

The rapidly aging population has posed a key challenge to China. More than 15.5 percent of the population, or 212 million people, were 60 or older by the end of 2014. The number could reach 300 million, or 18 percent, by 2025, according to estimates by China's National Working Commission on Aging.

"Many people still have 20 years of time after their retirement. People are concerned about how this group of people should spend their time," Wang Zhecheng said.

What the vocal group wants to display to the society is a new way of living for seniors, he said. "We hope our way of living can provide a reference for other elderly people."