How Wind Instruments
Make Sounds

In wind instruments like the flute and trumpet, vibrating air takes the place of vibrating strings. Strings travel from side to side when they vibrate. Inside a flute or clarinet, the air doesn't travel from side to side. It moves back and forth instead. Blowing across a flute's blow hole sets up Slinky-like waves in the tube. In the clarinet, a vibrating reed (a thin piece of wood set in the mouthpiece) gets the waves started. Different pitches are played by pressing keys that open or close holes in the tube. This makes the air column inside the tube longer or shorter. Like strings, longer air columns produce lower pitches.

Scientist's Corner
Here's an experiment to try. See how the length of a straw affects its sound.

What You'll Need
Scissors
Drinking straw

What To Do
1. Cut a triangular point in one end of the straw.

2. Lightly pinch the pointed end of the straw between your lips. Blow into the straw to make a buzzing sound. You have to blow pretty hard to get a sound.

3. While blowing, cut off short pieces of straw at the other end. Listen to what happens.

What You Discovered
The sound gets higher as you cut pieces off the straw.

Why?
Just as with vibrating strings, a shorter straw produces a higher sound. The vibrations travel a shorter distance. The short column of air gives the sound a higher frequency and pitch.

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This project is from Rubber-Band Banjos and a Java Jive Bass by Alex Sabbeth. Copyright © 1998. All rights reserved.