The jaw-harp is a lamellophone instrument, consisting of a flexible metal or bamboo tongue or reed attached to a frame. The tongue/reed is placed in the performer’s mouth and plucked with the finger to produce a note. Each instrument produces usually produces one pitch only, with its multiples [overtones].
Although the kouxian [as played in mainland China] is capable of playing five tones. This is achieved by tuning five individual jaw-harps the pentatonic scale and tying them together so they can be played as a single instrument.