Emperor Hirohito’s recorded radio address announcing Japan’s surrender is called Gyokuon-hoso. The term is commonly translated as “Jewel Voice Broadcast,” a reference to the emperor’s voice being heard by the Japanese public for the first time.
Hirohito recorded the address on August 14, 1945, and it was broadcast at noon on August 15 in Japan. In formal language, he announced that Japan would accept the terms of the Potsdam Declaration. The recording used classical court language that many listeners found difficult to understand directly.
Gyokuon-hoso was not the formal surrender document. The Japanese Instrument of Surrender was signed later, on September 2, aboard USS Missouri. The broadcast announced the decision to accept the Allied terms, while the instrument legally recorded the capitulation and ended hostilities in the formal ceremony.