The four-minute radio broadcast announcing Japan’s acceptance of surrender terms was called Gyokuon-hōsō.
Gyokuon-hōsō, often translated as “Jewel Voice Broadcast,” was Emperor Hirohito’s recorded address broadcast on 15 August 1945. It announced that Japan had accepted the Potsdam Declaration, although the Emperor used formal and difficult classical language rather than the plain phrase “Japan surrenders.”
The recording was made at the Imperial Palace and transmitted by NHK at noon Japan Standard Time. It was the first time many Japanese people had heard the Emperor’s voice. The broadcast followed political and military debate inside Japan, including an attempted coup by officers who wanted to prevent the surrender announcement.
Gyokuon-hōsō is not the name of the Potsdam Declaration or the later signing ceremony. It identifies the radio announcement itself, while the Instrument of Surrender was signed aboard USS Missouri on 2 September.