An accordion reed is a structure within an accordion that functions to create the instrument's sound. These structures operate on the principle of free vibration in order to produce a pitch. Each accordion reed consists of several smaller parts. The first is the reed plate, which is a flat piece of metal with two long holes, or slots, in it. The second is the strip of metal that vibrates as the player performs. Every reed plate holds two of these strips, or tongues, with the strips positioned on opposite sides of the plate. The strips connect to the reed plate via rivets.
Accordion makers position the tongues of accordion reeds so that they are almost parallel to the reed plate, with the tip of the tongue being a little above the plate. When an accordion player performs, air pressure builds up against the reed and pushes against one of the metal tongues to the point that the tongue is pushed through its corresponding slot in the reed plate. The release of this pressure causes the tongue to move back to its original position. This is what happens in one cycle of the reed's vibration, with many cycles happening per second to produce a pitch.
The tongues in accordion reeds operate in only one direction. This means that air must pass over the tongue first instead of the slot. Air from the wrong direction only causes the reed to bend, so no sound is produced. When a player expands the instrument, one tongue vibrates. When he pushes in the sides of the accordion, the other tongue vibrates.
Several different types of accordion reeds are available, with each reed type having its own characteristics. Commercial reeds are almost entirely produced by machine. These are the cheapest type of accordion reed but also the lowest quality. Tipo A Mano reeds are imitation hand-made accordion reeds and are of medium quality. The best reeds are handmade from Duraluminum, are finely finished until they shine. They may have the base of the tongues obscured by the wax used to secure the reeds to the reed block.
Typically, the tongue of an accordion reed is steel. Some tongues are made from brass, but this occurs less frequently. The metal used in accordion reeds makes an enormous difference in the sound and longevity of the reeds. Each type of metal has a different density, which means it takes different amounts of air pressure to get different metal tongues to vibrate. Different types of metal also oxidize at varying rates.
In addition to the metal used, the length and profile shaping of the reed tongue also influence the sound of the accordion reed. Other factors such as the size of the accordion also impact the sound. Master accordion makers work hard to construct reeds that take these factors into account so that players get the best possible sound.