An instrument that produces sound by blowing air across a reed (often called a tongue) to cause it to vibrate, however, the reed must vibrate freely, in other words it must not touch anything as it vibrates. The free-reed instruments can be broken into two categories, the Unframed Reed and the Framed Reed. The Framed Reed instruments have a frame that creates a path for the air to be directed against the reed to create vibration. The Unframed Reed instruments have no physical frame to force the air to act on the reed in a consistent manner. Below is a table of the free-reed aerophones in these categories. UNFRAMED REED INSTRUMENTS Air Source Instrument Wind Blown Bull-roarer Aeolian Harp Mouth Blown Leaf Instrument* Mouth Blown & Plucked Jew's Harp FRAMED REED INSTRUMENTS Air Source Instrument Mouth Blown Sheng Sho Harmonica Hand Blown Concertina Bandoneon Accordion Foot Blown Harmonium Reed Organ Pedal Concertina Mechanically Blown Barrel Organ Pedal Reed Organ Electric Chord Organ * This refers to a primitive free-reed instruments where sound is produced by stretching the reed (in this case a leaf, or a long blade of grass) between the thumbs and blowing across the reed with the mouth. The tips of the thumbs hold one end of the reed and the base of the palm just below the thumb holds the other end. The pitch can be raised or lowered by changing the tension on the reed with the thumbs. Cupping the hands can provide a sound chamber that will effectively change the quality of the sound. The thickness of the material used will also effect the sound.