Making a Straw Woodwind

This activity developed by Dr. Eric Arons, formerly of CUOS

Recommended Age: Later Elementary & Middle School

Questions

  How can you make a “reed” instrument?

  How do instruments make sounds?

  What determines the pitch of an instrument?

What You Need

• Paper and Plastic Straws
• Scissors
• Patience!

What You Do

1. Take straws and flatten one end.
2. Cut out a “V” shape in the flattened end of the straw (see figure).
3. The cut end of the straw acts like the reed attached to many woodwind instruments. Place the “reed” of the straw on your lower lip, close mouth gently—not too tightly—over it, and blow until it makes a sound. Don’t let your teeth touch the straw. With your lips barely touching, blow steadily, gradually increasing your lip pressure.
4. Once you succeed in making a noise, try snipping the end off the straw while you are blowing. What happens to the pitch (highness or lowness) of the sound?
5. Try cramming another uncut straw into the open end of your straw to make it longer. What happens to the pitch now?
6. Try cutting small holes along the top of the straw. Cover all of the holes with your fingers and blow into it again. Now lift different fingers to open the holes one at a time. What happens to the pitch?
7. Which straws are easier to make instruments from—paper or plastic (and why)?

What Is Happening

This experiment looks deceptively easy—but playing such instruments is harder than it it seems! That is why this activity is not recommended for early elementary students. Practice yourself first to get an idea of what is required.

Plastic straws are much easier to use, but paper ones have, in my opinion, a nicer timbre and they also present a nice challenge for strong-willed individuals. However, smaller children might get frustrated with paper straws. The secret to getting a sound is in not trying to blow too hard.

You have made a primitive double-reed instrument, since your “reed” has two sides that vibrate together to make a sound. Players of these instruments—such as oboe (pictured at upper left), bassoon, and English horn—spend a lot of time making and adjusting their reeds to get just the right sound. Experiment with different reed sizes and shapes (such as an upside-down “U” instead of a “V”) to see how it affects the sound.

Blowing into your instrument makes the air within it vibrate. The pitch depends on the length of the column of air. If you shorten the length—either by cutting the straw shorter or by letting the air escape through a hole in the side of it instead of at the end of the straw—you produce shorter wavelengths and higher-pitched sounds. Shorter wavelengths also have higher frequencies—that is, the waves are closer together. The measurement of frequency is called a hertz or “cycle per second.” The air in your straw instrument will have a frequency of a few hundred hertz. The frequencies produced by the largest double reed instrument, the contrabassoon, are so low that it can be difficult to tune, and the player actually has to blow some time before the note is needed, because it takes so long to get all the way out! If you look closely at a bassoon or a contrabassoon, you can see how the “tube” of the instrument is folded once or twice to make it long enough to produce really low sounds. The contra is really about 18 feet long!