Fading sound

Half of all hearing-loss cases are avoidable through primary prevention, according to a World Health Organization report. Liu Zhihua finds out the details.

Beijing resident Liu Wen almost fainted when the doctor informed her that her 5-year-old daughter Zhang Shiwen had profound hearing loss.

"I knew she might have some problem with her hearing, but it had never occurred to me the problem would be so severe," Liu says. "Doctors said even a train whistle would sound vague to her."