Emperor Hirohito’s recorded surrender broadcast is commonly called the Gyokuon-hōsō.
The term means “Jewel Voice Broadcast” and refers to the radio address transmitted to the Japanese public at noon Japan Standard Time on August 15, 1945. Hirohito read the Imperial Rescript on the Termination of the War, announcing that Japan would accept the Allied terms and end the fighting.
The recording had been made the previous day. Its classical Japanese language and the Emperor’s unfamiliar voice made it difficult for many listeners to understand immediately. The broadcast nevertheless became a defining moment in Japan’s transition from wartime mobilization to surrender.
Gyokuon-hōsō is not the name of the Potsdam Declaration, which was the Allied ultimatum issued on July 26. It is also separate from the Japanese Instrument of Surrender, which was signed aboard USS Missouri on September 2. The broadcast announced the decision; the instrument formalized it.