She then invited experts to teach and help the children, and sent members to different performance venues for shows in China and abroad. Other than singing at CCTV shows, the choir participated in such events as the World Choir Contest in Sochi, Russia, in 2016, and the Johannes Brahms Choir Festival in Germany, in 2017.

The choir of 28 members-all from Tianjin, aged from 5 to 15, including her son-performed at the opening ceremony of the 10th National Para Games of China and the Seventh Special Olympics on Sunday, twin events with a common opening ceremony, according to the organizers.

"The children could sing a narrow range of tunes, but they tried their best to present the songs to the audience," Xiao says.

During the event, the choir sang two songs, Big Sky and You Can, I Can, both composed with their condition in mind.

Some of the children simulated the movement of their teachers' mouths while singing.

"I saw some cry as it was hard for them to sing," says Meng Ke, director of the opening ceremony.

Xiao says hearing-impaired children can't hear different sounds and with little interaction in their silent world, their vocal cords also decay with time.