What was the recorded radio address by Emperor Hirohito called?

The recorded radio address by Emperor Hirohito was called the Gyokuon-hōsō.

The Japanese term is commonly translated as “Jewel Voice Broadcast,” referring respectfully to the emperor’s voice. It was broadcast on 15 August 1945 and announced that Japan had accepted the terms of the Potsdam Declaration. The address is also associated with the Imperial Rescript on the Termination of the War.

Hirohito’s speech was recorded on phonograph discs at the Imperial Palace on 14 August. The official recording was played over NHK at noon the next day. Because the emperor spoke in formal classical Japanese and the audio quality was poor, many listeners did not immediately understand that Japan had surrendered.

The broadcast announced the political decision to end the war, but it was not the legal signing of surrender. That formal act occurred on 2 September 1945, when Japanese representatives signed the Instrument of Surrender aboard USS Missouri in Tokyo Bay.