A large – and loud – piece of history is on display in the coastal Chinese city of Xiamen. It's home to the world's largest military loudspeakers - which was used for decades to broadcast policies to Taiwan. Now people from both sides of the Taiwan Strait are visiting the park. Our reporter Li Jianhua has more. 

LI JIANHUA Xiamen "Loudspeakers aren't rocket science. They are ubiquitous – you can find them in your home, in the markets or in the airports, you name it."

But what you may not know is loudspeakers are also widely used during wartime.

This is the world's biggest military loudspeaker, with its length reaching nearly five meters, and diameter nearly three meters, its sound – powered by compressed air – could travel by 12 kilometers.

In 1958, tensions between the Chinese mainland and Taiwan escalated. This islet was heavily bombarded, with bombs fired all the way from Kinmen, about six kilometers away. It is said each square meter of this region received a bomb and a half.

The loudspeaker was used in psychological attacks against Taiwan. Two variants of the Chinese language – Mandarin and Hokkien – were used, with broadcasts ranging from the Chinese mainland's Taiwan policies and social achievements, to notices for missing relatives across the strait.

The speaker is no longer used by the military with broadcasts being reduced to a murmur in 1991.  This is the place where the radio announcers used to work, and now it has become a museum.

In 2010, two radio announcers from both sides of the Taiwan Straits met here for the first time, a sign of rapprochement between the Chinese mainland and Taiwan. I'm not sure how they felt at that particular moment. They were once opponents, but they seem more like friends in this picture.