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. Referring to music, Pitch is used to describe how high or low a note is. It depends on the frequency (number of vibrations per second) of the sound, which is measured in hertz (Hz). Higher pitches = increased frequency = shorter wavelengths. As pitch gets higher, wavelength gets shorter. Pitch also refers to the standard to which instruments are tuned. Sometimes the pitch can be changed by opening or closing holes in the air column. The longest column of air produces the lowest note. The woodwind family of musical instruments uses the vibrations of a column of air to form notes. The range of notes produced by each instrument is primarily determined by the length of the instrument – for example, the piccolo produces much higher notes than the bassoon.

Pre-Lab Questions: Use complete sentences for full credit 1. Define Pitch. How can pitch be altered?

2. How do wind instruments produce sounds?

3. Based on the background info, which woodwind instrument would produce the highest note? Which would produce the lowest note? Explain your answers.

4. How does pitch affect the wavelength of a sound?

Materials : 8 test tubes, Beaker, Test tube rack, Eyedropper / Pipette , Ruler, Water, 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 Water Note Test tube Water Note Height Height Test tube 1 No water Middle C Test tube 5 5.5 cm G Test tube 2 2 cm D Test tube 6 6.5 cm A Test tube 3 4 cm E Test tube 7 7.5 cm B Test tube 4 5 cm F Test tube 8 8.5 cm 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 the correct note.

4) Using your test tubes, play the simple tune below for the class. Please don’t put your mouth on the test tubes. 5) Fill in the data section, using what you have heard from listening to the test tubes.

6) Discard your water and dry your glassware.

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 when you blew air across the top of it.

What does the length of the air column tell you about the wavelength of the sound wave or air inside the column? Test tube: Length of air column Increased or decreased pitch: Longer or shorter wavelength: (cm): 2 7 5 1 3 8 6

Discussion : 1) What caused the sound you heard when you blew across the top of the test tubes?

2) Which test tube had the longest column of air?

3) Which test tube produced the highest pitch?

4) Which test tube had the shortest column of air?

5) Which test tube produced the lowest pitch?

6) What is the relationship between the length of the air column and the pitch of the sound?

7) Name one instrument that makes sound the same way that the test tube does.