The hurdy-gurdy is a stringed instrument that produces sound via a crank-turned, rosined wheel rubbing against the strings. The wheel functions like a violin bow, but since it is continuous, it can produce sound indefinitely. The instrument features 'drone' strings that provide a constant pitch and 'melody' strings that are shortened by wooden keys (tangents). One of its most distinctive features is the 'dog' or buzzing bridge; when the player cranks the wheel with a rhythmic burst of speed, the bridge vibrates against the soundboard, creating a rhythmic buzzing sound used for percussion. Originally a large instrument played by two people in monastic settings, it evolved into a portable folk instrument. Today, it is experiencing a revival in folk-metal and experimental music due to its unique, drone-heavy, and mechanical sound which bridges the gap between a bagpipe and a violin.