Created by Dale Olive and Randy Scoville
Future Flight Hawai`i instructors
Demonstration at a glance:
Two small quarter inch pieces are cut off the end of a straw leaving a triangle piece remaining. When the cut side is placed in the mouth and blown through, a loud sound is heard. As the end of the straw is cut one inch at a time, the pitch goes up.
I chew the end of the straw to flatten it before cutting. It took me a while to figure out how far I should place the straw into my mouth to get the sound. I get a good sound with about 2-3 inches inside my mouth.
Cutting the straw in this manner creates a reed much like the ones used in wind instruments. By blowing through the reed, the ends vibrate creating sound. Pitch is related to how long the vibrating column is. The longer the column, the lower the pitch.
You can further demonstrate this concept by blowing into a test tube with varying amounts of water. The longer the air column above the water, the lower the pitch.
Communications: Hawaii Space Grant Office
This activity is featured in Future Flight Hawaii, a K-12 Education Project of Hawaii Space Grant Consortium.
FEB 27 2001.