By Daniel Griffiths BBC News, Beijing

The sounds of Mozart echoed around the Central Conservatoire in Beijing, and a young soprano stood beside a sleek black piano, watched by an audience of more than 50 people.

It was practice time at one of China's most prestigious musical institutions.

Some 30 million children are learning the piano in China

During the chaos of the country's Cultural Revolution, the Communist party clamped down on both traditional and foreign arts.

One of the worst affected areas was Western classical music. Considered decadent and bourgeois, many performers faced persecution or prison sentences. Some committed suicide.

But now, after years of neglect, classical music is making a comeback in China.

Today, there are around four million professional musicians, and new concert halls and opera houses are being built across the country.

'Most beautiful voices'

Another sign of change is the presence of the man putting the students through their paces at the Central Conservatoire - the legendary Italian tenor, Carlo Bergonzi.

Now in his 80s and leaning heavily on his silver-topped cane, he was once one of opera's greatest stars. He has worked with Chinese performers around the world.

"Without a doubt they are among the most beautiful voices in the world at the moment," he said.

"My work in Beijing is to uncover new talent, and many of the voices here today are first class. I can go home to Italy and say to friends that there are some wonderful singers here."

China opened the door to the world after the Cultural Revolution, and now millions of children are studying piano and violin Hao Jiang Tian, musician

Li Yang was among the students performing in the packed hall - now one of millions of young Chinese studying not just opera, but all forms of classical music. And like many of them she has a dream.

"Being here today is such a great opportunity," she told me.

"Carlo Bergonzi is such a wonderful teacher and an amazing singer. He has really helped me develop and help me bring out my own natural ability. Now I am thinking that perhaps after I graduate I would like to go and study in the US and take my career to a new level."

The organiser of the master class, Hao Jiang Tian, is now one of the New York Metropolitan Opera's superstars, against the odds.

During the Cultural Revolution, his piano teacher was thrown into prison. His musician parents destroyed all their classical records to avoid the same fate, and many of their colleagues committed suicide. Hao Jiang Tian was sent to work in a factory.

Mr Hao said that the economic reforms of recent years had finally led to cultural change as well.

"China opened the door to the world after the Cultural Revolution" he said, "and now millions of children are studying piano and violin, and thousands of young people are studying singing."

Aspirational

In fact, some unofficial reports estimate that 30 million children in China are learning to play the piano. Many of them are the offspring of the country's new middle class.

Their competitive parents are eager to make sure that their sons and daughters have everything that they were denied in their youth.

"I have seen more and more people interested in classical music," Mr Hao said, "and so I am, you know, very happy, because the future of classical music will be in China because there are so many young talents."

In fact, China is now producing some of the world's most exciting singers and performers - pianists like Lang Lang and Li Yundi, and the composer Tan Dun.

So music in China has moved from the depths of despair to international success in a few short decades.