"But when volunteers explain and tell parents their children can speak after they spend two years or so on AVT, many parents will give it a try."

In 2001 Nichols died, and Cheng became the force behind the foundation.

To date, more than 3,000 hearing-impaired children in Taiwan have benefited, and 99 percent of them now attend normal kindergartens or schools, Cheng says.

"When children use sign language or lip-read, they need to watch people. They cannot make phone calls, or do other things at the same time," Cheng says.

"With AVT training, the children can listen and speak."

On the Chinese mainland, the foundation has donated about 4 million yuan ($662,000) to train therapists and equip classrooms.

Hu Xiangyang, director with the China Rehabilitation and Research Center for Deaf Children, says the foundation is very generous in helping their center promote AVT on the Chinese mainland.

But not everyone welcomes AVT. In the United States, some therapists believe sign language is the preferred way to empower hearing-impaired people, and refuse to use AVT, Cheng adds.