Emperor Hirohito's first radio address heard by the Japanese public was called Gyokuon-hōsō.
Gyokuon-hōsō literally refers to an imperial voice broadcast and is the common Japanese name for the 15 August 1945 radio transmission. Hirohito read the Imperial Rescript on the Termination of the War, announcing Japan's acceptance of the Potsdam Declaration.
Most Japanese citizens had never heard the Emperor's voice before this broadcast. The recording had been made on 14 August, hidden during an attempted military coup, and then transmitted after the plot failed. The recording quality and the formal classical language made it difficult for many listeners to understand immediately.
Gyokuon-hōsō is often translated descriptively as “Jewel Voice Broadcast,” but that English phrase is not the name of a separate treaty or document. The underlying text was the Imperial Rescript, while Gyokuon-hōsō identifies the broadcast event.