
right|thumb|upright=1.3|Bullroarers from Africa in the Pitt Rivers Museum
right|thumb|upright=1.3|Bullroarers from Africa in the Pitt Rivers Museum
The bullroarer, rhombus, or turndun is an ancient ritual musical instrument and a device historically used for communicating over great distances. It consists of a piece of wood attached to a string, which when swung in a large circle produces a roaring vibration sound.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).