Challenged by musical scores, students master singing through memorization.

When God closes a door, he opens a window, the saying goes.

For 18-year-old Zeng Xiaomeng — who lost her sight a few months after she was born due to an illness — her angelic voice is that window. Many remark on the celestial sound of her singing.

In a video of Zeng and three of her schoolmates singing — posted on the internet by their teacher — their beautiful voices have amazed and touched many.

"Thanks to your encouragement and blessings, your openness and praise, we will sing better and live better," the four girls have replied to the messages they receive.

Years ago, when Zeng realized she enjoys music, she talked to her parents about learning to sing. She started her school days at Hengyang Special Education College in Hunan province 11 years ago.

"She has a gift for music and learns songs faster than others," said Zhang Xuemei, Zeng's teacher at the school.

"It is not easy for visually impaired students to learn to sing. They need to use Braille while I read the lyrics. They also need to practice the melody and rhythm repeatedly. It takes up to a month to learn a song."

Repetition is a major learning method for Zeng and the other three girls in her chorus.

"You have to listen to the song many times to learn the emotions behind the lyrics, and when I encounter problems I will ask teachers and friends for help," Zeng said.