What was the formal English nickname of Hirohito's August 15, 1945 surrender broadcast?

The formal English nickname of Hirohito’s August 15, 1945 surrender broadcast was the “Jewel Voice Broadcast.”

The Japanese name is Gyokuon-hōsō. The term refers respectfully to the emperor’s voice: “jewel” or “jade” language was a traditional expression associated with imperial speech. The broadcast announced Japan’s acceptance of the Potsdam Declaration and effectively told the public that the war would end.

The message was not transmitted live. Hirohito recorded it on a phonograph record late on August 14, after Japan’s leadership had decided to accept the Allied terms. Army officers opposed to surrender attempted to seize the recording during the Kyūjō incident, but palace staff hid and protected it.

At noon on August 15, the recording was played over NHK radio. Its courtly language, unfamiliar pronunciation, and weak audio made it difficult for ordinary listeners to follow. A broadcaster then clarified that Japan had surrendered, preventing confusion about the announcement’s meaning.