Musical Test Tubes
Background:
Music, like any other sound, is produced by vibrations. Wind instruments such as the clarinet, flute and trumpet,
make sound by making the air inside the instrument vibrate. These instruments are called wind instruments
because air is needed to create the sound. Sometimes the pitch can be changed by opening or closing holes in
the air column
Materials:
8 test tubes
Water
Test tube rack
Eyedropper
Ruler
Masking tape
Procedure:
1) Fill eight test tubes with water according to the instructions below. Each test tube should produce a note close
to the one listed below. Measure the height of the water from the bottom of the test tube.
Test Tube
Test tube 1
Test tube 2
Test tube 3
Test tube 4
Height
No water
2 cm
4 cm
5 cm
Note
Middle C
D
E
F
Test tube
Test tube 5
Test tube 6
Test tube 7
Test tube 8
Height
5.5 cm
6.5 cm
7.5 cm
8.5 cm
Note
G
A
B
High C
2) Blow across the top of the test tube. Each test tube should make a different note. You may have to adjust the
height of the water slightly using the eyedropper.
3) Use small pieces of masking tape to label each test tube with a number and the correct note.
4) Copy the chart on YOUR paper. Answer the questions on YOUR paper. EACH PERSON should have his or
her OWN paper with the data chart and discussion questions.
Data:
First, fill in the length of each air column (notice they are not in order).
Using test tube #4 as a reference sound, note if you heard a higher or lower pitch (compared to test tube #4)
when you blew air across the top of it.
Test tube: Length of air
column (cm):
2
7
5
1
3
8
6
Increased or decreased
pitch:
Longer or shorter
wavelength:
Discussion:
1) What caused the sound you heard when you blew across the top of the test tubes?
2) How did changing the lengths of the air columns in the test tubes affect the sounds produced? Be specific.
3) What is the relationship between the length of the air column and the pitch of the sound?
4) How is the length of the air column for the lowest note of the scale related to the length of the air column for
the highest note?
BONUS—Play the song for the teacher: Using your test tubes, try to play the simple tune below. Note: the
filled-in circles are 1 count; the unfilled circles are 2 counts. Suggestion: assign a note (C, D, E, F, G) or two
per person in your group.
MORE BONUS: What is the name of the song you’re trying to play?