How does the accordion work?
The accordion is a free-reed instrument, much like a harmonica or harmonium. The reed produces sound when air passes across it, setting it into vibration. A free-reed means the reed moves back and forth in a slot when air passes across it. In a free-reed instrument, each reed produces ONE pitch, depending on its length and thickness.
Accordion reeds are made of metal and two distinct reeds are required for each key, one activated when the bellows are pulled, one when the bellows are pushed. (As stated earlier, a chromatic accordion has the same pitch whether pulling or pushing, which means the two reeds are identical, while a diatonic accordion has a different pitch when the bellows are pulled or pushed, which requires two different reeds.)
These reeds are placed in a reed block, arranged by pitch succession, low to high. One set of reeds like this in an accordion produces one distinct timbre or tone color.
A full-sized accordion can have as many as 448 reeds since there may be 4 reed-blocks for the right hand and 5 for the left. Good reeds, particularly those that are hand-crafted, are both heavy and expensive. Each reed may cost c. $7.00 or more in the crafting process in a quality accordions. In addition, a full-sized accordion can weigh about 30 pounds.