A thin piece of cane, plastic, or metal used as the principal vibrating source many instruments. A single reed vibrating against the mouthpiece of the instrument would be found in the clarinet and clarinet families. Double reeds vibrate against each other and are found in the oboe and bassoon families. A free vibrating reed (that doesn't vibrate against anything) can be found in the harmonium, harmonica, and accordion. Metal reeds are typically only found in the pipe organ, harmonium, harmonica, concertina, bandoneon, and accordion.a piece of cane or metal in the mouthpiece that vibrates to produce sound when air is blown across it