…of an accordion are the free reeds, small metal tongues arranged in rows alongside pallets (valves) that are cut into metal frames. When air flows around a reed from one side, it vibrates above its frame; airflow in the opposite direction does not cause vibration. Wind is admitted to the…

…which sound is produced by free reeds. Accordions and concertinas are examples of small, hand-held reed organs. Free reeds are thin, flexible strips of metal, usually brass, that are secured at one end over or under close-fitting openings in plates that are mounted over a wind-chest. Suction or wind pressure…

They contain free reeds, which vibrate above or through a slot, setting the air into pulsations. The resulting pitch is determined by the thickness and length of the vibrating reed.