melodeon, keyboard instrument sounded by the vibration of free reeds by wind. It is an American development of the harmonium, from which it differs in two principal respects. Its foot-operated bellows draw the air in past the reeds by suction, rather than forcing it out by pressure; and the characteristic size and form of the reeds and resonators result in a more even dynamic level throughout the compass. It was slower to respond than the harmonium but sounded more organlike and had a softer tone.