Hornbostel - Sachs
Idiophonic interruptive aerophones or reeds
Reed instruments that are free aerophones are sounded by a flow of air in which the reed is the primary vibrator. The vibrating air is not confined by the instrument. The air-stream is directed against a lamella, setting it in periodic vibration to interrupt the stream intermittently. Two lamellae make a gap which closes periodically during their vibration. A split grass-blade.
Idiophonic interruptive aerophones or reeds: paired reeds