Bull roarer is a propeller-shaped piece of hardwood made by Aboriginal people of Australia. When swung on the end of a cord, it spins at a great speed and produces a loud moaning sound. The Aboriginal people used bull roarers in secret ceremonies. Women and children accepted the sound as a warning to keep away from the sacred ceremonial grounds. Aboriginal people in parts of Arnhem Land swung as many as 20 bull roarers at the same time as a climax to certain ceremonies.
