The bawu is a Chinese wind instrument. Although shaped like a flute, it is actually a free reed instrument, with a single metal reed. It is played in a transverse (horizontal) manner. It has a pure, clarinet-like timbre and its playing technique incorporates the use of much ornamentation, particularly bending tones.

A free reed aerophone is a musical instrument that produces sound as air flows past a vibrating reed in a frame. Air pressure is typically generated by breath or with a bellows. In the Hornbostel–Sachs system, it is number: 412.13. Free reed instruments are contrasted with non-free or enclosed reed instruments, where the timbre is fully or partially dependent on the shape of the instrument body, Hornbostel–Sachs number: 42.