With her chant of "Nothing about us, without us", a disability empowerment slogan, Zheng Xuan, a deaf expert on Chinese Sign Language, finds herself almost alone.

For generations, linguistic research into CSL has been dominated by people with unimpaired hearing.

"I am one of a very small number of deaf people in the field," said Zheng, a specialist in deaf education at Beijing Normal University, China's top teacher training college.

In 2016, a Confucius Institute in Minnesota, United States, wanted to recruit deaf Chinese teachers for an exchange program. As someone who could use spoken Mandarin and English and was also a longtime user of CSL, the 40-year-old had no rivals.

The stigma attached to using sign language－a telltale sign of hearing loss－has led many high-achieving deaf people to learn oral languages.