How a Harmonica Works

When learning how to play the harmonica, it is important to learn how a harmonica works. The diatonic harmonica is the smallest and simplest of the free reed instruments which include the:

• concertina
• accordian
• melodeon
• harmonium or American organ, and
• Chinese sheng

In these musical instrument, each reed (a brass strip attached at one end to a brass frame or base) vibrates freely when air is moved from the unattached end to the other. The harmonica is the only one in which this process is controlled and directed solely by the mouth. All the other instruments have buttons or keys. The mouthpiece assembly can be made of wood or plastic, and the casing on which the lips rest is usually metal.

Each hole of a diatonic harmonica mouthpiece is a tunnel to two free reeds, placed at the top and bottom of the tunnel. The top reed, with the unattached end near the mouth hole, vibrates when it is blown, and the bottom reed, with the unattached end away from the mouth hole, when it is sucked, or drawn. Each mouth hole thus produces two notes, which are tuned to be next to each other on the scale.

Diatonic harmonica - top reeds

Diatonic harmonica - bottom reeds

Diatonic harmonicas are produced in range of keys: C, D, E, F, G, A and Bb. A 12 hole harmonica in the key of C has a range of three octaves, starting and ending on C. the notes are equivalent to the white keys on a piano keyboard with the lowest harmonica C being middle C on a piano.