How it works
The parts of a harmonica are a comb, two reed plates and two cover plates. The first drawing takes a ten-hole harmonica apart; the second shows the mouthpiece and slide of a chromatic one.
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A harmonica, taken apart
The comb is the body in the middle. Its teeth divide it into air chambers, one behind each hole. A reed plate lies on each side of the comb. Each plate carries a row of reeds, thin metal strips fixed at one end over a slot. A cover plate goes over each reed plate.
A chromatic harmonica
A chromatic harmonica has a mouthpiece across the front and a slide behind it. Pressing the button at the end of the slide sends the air to a second set of reeds. Windsavers are small flaps over the slots; they stop air leaking past the reed that is not sounding.
Questions and answers
Why is the middle of a harmonica called a comb?
The comb is the main body, with a row of teeth that form the air chambers. The name may come from its likeness to a hair comb.
What are the metal plates on a harmonica called?
The two outer ones are cover plates. Under each is a reed plate, a flat plate that holds a row of reeds. The reeds are usually brass.
How many reeds does a ten-hole harmonica have?
Twenty: one row of ten that sound when you blow, and one row of ten that sound when you draw breath in.
What does the slide on a chromatic harmonica do?
Pressing its button moves a bar behind the mouthpiece, so the air from each hole goes to a second set of reeds. That gives the sharps and flats.