A series of seminars featuring industry heavyweights, including Chung, China Entertainment Television Broadcast founder Robert Chua and veteran DJ Ray Cordeiro, have traced the evolution of radio and TV productions. The celebrations will culminate on August 13, when the exhibition '75 Years Of Broadcasting In Hong Kong' opens at the Museum of History. It will feature nostalgic items such as studio equipment used in the 40s, a weather script related to the infamous Typhoon Wanda in 1962 and black-and-white photos of singers and broadcasters. The exhibition, which runs until September 22, encompasses radio and TV broadcast, although the former features more prominently because of its longer history.

Chung, who will be one of the official guests, has offered some of his possessions for the show, including an MBE he was awarded in 1992 for his contribution to radio (he was the first Chinese broadcaster to receive the honour) and a stamp collection related to broadcasting.

He says fond memories of those radio days came flooding back when he searched through his possessions a few months ago for items to donate to the exhibition. 'The past was full of challenges - I often played one character in one radio drama in the morning and a different one in another drama in the afternoon,' he says. 'A day passed quickly ... then a week, a month, a year. I feel like the past few decades have passed in a flash.'

Chung, who now hosts the music show Programme For The Elderly and the health-related phone-in programme Senior, recalls the old days with a touch of nostalgia as he sits in a recording room at RTHK's studios in Broadcast Drive, Kowloon Tong. When asked what he thinks about the current generation of broadcasters, he answers diplomatically. 'I don't like to criticise people,' he says, but adds, 'young people should avoid lazy Cantonese pronunciation.'

Chung is in a good position to comment. His years in the industry have fine-tuned his speech - he utters every word clearly without sounding pretentious, a commanding voice that many consider perfect for broadcasting. But it was only chance that brought one of Hong Kong's best-known voices to radio. Chung's dream had been to be a film-maker, and he was working as a film company assistant in 1947 when a friend invited him to an audition at what was to become Radio Hong Kong the following year and Radio Television Hong Kong in 1976. He impressed and began working in radio dramas on a freelance basis.

In 1952, Chung's broadcast career formally began as he joined the now-defunct radio station Rediffusion. After a few years he moved across to the US Information Service, (which closed in the 1970s) and had various other broadcasting jobs before moving to what is now RTHK in 1970.

'When I worked for Rediffusion, people had to pay $10 a month to subscribe to the service,' Chung says. 'A bowl of rice with roast pork was just 10 to 20 cents. But radio wasn't really a luxury because the licence was free and the company would pay the electricity bill for subscribers.'

Chung stuck to radio dramas and was a regular performer during its golden age from the 50s to the 70s. 'Radio dramas were not only popular in Hong Kong. In Singapore and Malaysia, some shops would close when the hit shows were on so the shopkeepers wouldn't miss the stories,' he says.

Chung always played the lead characters, including a quick-thinking detective and a righteous warrior. To excel in his various detective roles, such as that in the long-running series, The Detective Story Of Kwok And Lam, he joined the auxiliary police. 'I worked at night as a cop for two years. In the 50s, adults born in Hong Kong had to perform public service. I chose to be a police officer because I was to play a role as a detective. I wanted to learn how the police force operated to do a better job in the drama.'

Chung says such extra research was essential due to the different nature of radio dramas, in which more emotion and expression has to be conveyed through the voice as the actors cannot rely on anything visual. 'Not being seen makes acting harder. You have to be completely engrossed in the role to convey the character's feelings through your voice. And it was not easy having to play different roles with the same voice,' he says.

Performing came more easily over the years, but live broadcasts brought added pressure to avoid blunders. Chung recalls one incident when he had to improvise to prevent a show being ruined. 'One day when we were doing an episode in which I played a detective, some folded chairs in the studio suddenly crumbled like dominos and caused this thundering noise. I immediately improvised by asking my colleague who played my subordinate, 'What's all this noise about?' ' To Chung's relief, the colleague was equally quick-witted. 'I don't know,' he said. 'Let me check ... Oh, detective, some people were fighting outside.' An embarrassing episode was avoided. 'I didn't know how I managed to blurt out the line,' Chung says. 'But we were lucky.'

Hong Kong's output of radio dramas peaked in the 70s, with an average of 52 hours a week. But as television became more popular, fewer dramas went to air. Today, the 35-year-old Commercial Radio programme 18/F Block C takes the prize for the longest-running radio drama in Hong Kong history.

In radio, the place of dramas has been usurped by talk shows and phone-in programmes. Cheng Kai-ming, deputy head of RTHK's Radio 5 and co-ordinator of the exhibition, puts the trend down to the prohibitive cost of production.

'In the past, when television was still undeveloped, radio dramas on stations such as the Commercial Radio were supported by a tremendous amount of advertising. And RTHK was driven by the phenomenon to produce more dramas,' he says. 'Now radio dramas have become the most expensive to produce because the studio hour is long and you have to pay for the script and the celebrities.'

Chung says the decline of radio dramas is a shame. 'They can trigger so much imagination - you hear the voice of a character and an image will be formed in your mind, which is different for different people. It can be Audrey Hepburn for me and [veteran actress] Ka Ling for you. This is where the appeal lies.'

Does he think radio dramas might one day enjoy a revival? 'It's impossible,'' he laments. 'Nothing can be done.'