The hurdy-gurdy is a stringed instrument. The various strings are rubbed into vibration by a wheel in stead of a bow like at the violin. The hurdy-gurdy is a drone instrument. Like at a bagpipe, one or more drones sound continously. Melodies are played on a keyboard that presses tangents (small wedges) against some of the strings to change their pitch. The highest-pitched drone string (the trompette) allows to play a rythm using a fancy mechanical feature (the buzing bridge). Thus, this cross-breeding product between a violin and a bagpipe approaches truly a medieval synthesizer.