After the performance Friday, Zhang appeared at a news conference with Chinese reporters and praised Miaoke. "She's very cute and sings quite well, too," he said.

Asked to name which section of the show he found most satisfying, he first mentioned Miaoke. "I was moved every time we did a rehearsal of this, from the bottom of my heart," he said, according to a transcript of the news conference.

Miaoke's song was considered critical because it coincided with the arrival of the national flag inside the massive National Stadium, also known as the Bird's Nest. In his radio interview, Chen said that an unnamed member of the ruling Communist Party's powerful Politburo attended one of the final rehearsals, along with other officials, and demanded that Miaoke's voice "must change."

By Tuesday, the Chinese media had pounced on the story, instigating a national conversation that government censors were quickly trying to mute by stripping away many, but not all, of the comments posted online.

The outrage was especially heated over the cold calculation used to choose between the girls.

"Please save the last bit of trueness in our children," wrote one person with an online name of Weirderhua. "They think Yang Peiyi's smile is not cute enough? What we need is truth, not some fake loveliness!"

Another person added: "Children are innocent. Don't contaminate their minds!"

Lin, the father, said he learned of the voice switch when he saw a video clip of the interview by the musical director, Chen. In that interview, on a program called Beijing Music Radio, Chen depicted the process of selecting a singer as a tortured ordeal. He said about 10 children were chosen who "had a good image and who can sing well." Initially, a 10-year-old was selected "whose voice was really good" and who had held the role for most of the rehearsal - until Zhang decided she was too old.

Then, Chen said, the desired age of the singer was lowered and several young girls, including Miaoke and Peiyi, were taken to the Central People's Radio Station in Beijing.