Recommended Age: Later Elementary & Middle School
How can you make a “reed” instrument?
How do instruments make sounds?
What determines the pitch of an instrument?
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