NHK replayed Hirohito’s surrender recording on August 15, 1945.
NHK was Japan’s national broadcasting organization, then known as the Japan Broadcasting Corporation. Its technicians recorded the emperor’s message at the Imperial Palace and later transmitted the official phonograph recording to stations around the country.
The broadcast was carefully arranged because the emperor had never before addressed ordinary Japanese citizens by radio. NHK announced in advance that an important imperial message would be heard at noon. The recording was replayed rather than transmitted live, partly because the message had been recorded during the night and reviewed before broadcast.
The broadcast was also endangered by a military coup attempt. Officers opposed to surrender tried to seize control of the Imperial Palace recording and the NHK station, hoping to prevent the message from reaching the public. They failed, and NHK broadcast the recording as planned. The event is now commonly known as the Jewel Voice Broadcast.