Pipes Tall as Trees: How an Organ Breathes
A pipe organ may be the largest instrument in the world. In a big church or hall, its pipes can climb the wall like a forest of metal trees. Some are as thin as a pencil, while others are taller than a house. Yet the whole giant is played by one person sitting at keys.
An organ does not have strings to pluck or drums to hit. It uses air. A blower pushes wind into a large box. When the player presses a key, a small door opens, and wind rushes into one pipe. The air makes the pipe hum with sound, much like blowing across the top of a bottle.
The size of a pipe decides the note. Short pipes make high, light notes. Long pipes make deep, rumbling ones. Because each key opens its own pipe, a player can make a huge range of sounds.
An organ also has knobs called stops. Pulling a stop selects a whole row of pipes that share a special tone. One row may sound like a flute, and another may sound like a trumpet. By choosing different stops, the player can make the organ sound like many instruments, even though only one set of keys is being played.