The Structure of the Harmonica
Learn the names of the parts

The most typical type of harmonica, in which a single reed is played when a note is produced, is the single-reed harmonica, also simply called the single harmonica.

Names of the parts of the harmonica

The entire display
  • body
  • cover
  • plate
  • reed
  •  mouthpiece

*Select any name to zoom in on the part.

Opening a harmonica's cover reveals yellowish metal. This sheet-like object is the plate.
On top of the plate are fastened several long, thin reeds.
Although they are hidden from view, underneath the reeds are rectangular apertures. The reeds and the apertures have geometrically similar shapes. The apertures are one size larger, and there are tiny gaps to the left, right, and tips of the reeds. That is, there is complete clearance beneath the reeds.
The reeds themselves are shaped like the letter T. The spots where the reeds are visible and where they are not alternate. Even in the spots where they are not visible, there is a reed on the bottom side with the T shape facing the opposite direction.

The reeds are affixed in an alternating fashion because the harmonica has both blow notes and draw notes. The reeds visible from the top side will not sound if blown but will sound if drawn; the reeds on the unseen bottom side, by contrast, sound if blown. In other words, blow reeds and draw reeds are lined up in an alternating fashion.
Basically, C, E, and G are blow notes, and D, F, A, and B are draw notes.

Diagram of a reed

Diagram of a reed
When the player draws the top reed, When the player blows the bottom reed, vibrates and produces sound.

Cross-section of a single-reed harmonica

Cross-section of a single-reed harmonica

Structurally, all notes could be made blow notes, but, if that were the case, there would need to be spaces left so that neighboring reeds do not sound, which would mean more moving of the mouth left and right, making playing more difficult. Also, if the player performed just by blowing without inhaling, it would be painful, even performing a single phrase. It is the blowing plus the drawing that allows a harmonica player to perform tunes smoothly.