What was Emperor Hirohito's 1945 radio announcement of Japan's surrender called?

Emperor Hirohito's 1945 radio announcement of Japan's surrender was called the Gyokuon-hōsō.

The Japanese term means “Jewel Voice Broadcast.” Hirohito recorded the speech on August 14, 1945, and it was broadcast at noon on August 15. In it, he announced that Japan had accepted the terms of the Potsdam Declaration and instructed the Japanese people to endure the otherwise unbearable.

The broadcast was historically remarkable because most Japanese citizens had never heard the emperor's voice. The recording used formal court language, so many listeners did not immediately understand that it represented surrender. The announcement preceded the formal signing of the surrender instrument by more than two weeks.

Gyokuon-hōsō is often confused with the name of the surrender document itself. The broadcast was an imperial announcement; the Japanese Instrument of Surrender was the legal document signed aboard USS Missouri on September 2.