A quadruple reed is a type of reed by means of which the sound is originated in various wind instruments. The term "quadruple reed" comes from the fact that there are four pieces of dried palm leaf vibrating against each other, in pairs. The quadruple reed operates in a similar way as the double reed, but produces a different timbre.
Instruments which use quadruple reeds
References
Quadruple reed Wikipedia(Text) CC BY-SA