What Materials Affect the Length of Sound?

Type:

Physics

Objective:

This experiment will explore how mallets of various materials and weight create sonic tones of varying lengths.

Research Questions:

-Does the material of a mallet change the length of a tone?

-Does the weight of a mallet change the length of a tone?

Introduction:

Musicians are always experimenting on how to alter and manipulate different tones. Knowing how to produce a certain tone is important in composition. This experiment will measure how material and weight changes the sound decay of a note.

Materials:

• Xylophone
• Hard rubber mallet
• Medium rubber mallet
• Yarn mallet
• Plastic mallet
• Spoon
• Drumstick
• Tape recorder
• Stopwatch
• Postal scale
• Notepad

Experimental Procedure:

1. Weigh each mallet on the postal scale. Note down the different weights.
2. Turn the recorder on.
3. With a light flick of your wrist, strike any one bar of the xylophone with the hard rubber mallet (like Middle C, but it doesn’t matter for our purposes). Note down in your notepad the quality of the sound (was it soft, woody or bright? Be specific).
4. Wait for the tone to become totally inaudible.
5. Keeping the recorder on the same time, repeat step 3 for every other mallet and for the spoon and drumstick. Remember to always strike the same note on the xylophone and with roughly the same force.
6. Turn off the recorder.
7. Using the recording and stopwatch, time how long it takes for each sample to resonate. Start from the moment the tone begins and time until the tone is completely inaudible. Write down the time of each sample.
8. Analyze all the data. Graph weight versus decay time. Does weight affect sound decay? How about material? How does the weight and material affect the quality of the tone? What type of mallet would you recommend to a musician looking to create a soft, long tone or a sharp, staccato tone?
9. For further research, try the experiment using a vibraphone, glockenspiel, or marimba. You could also try other materials that aren’t mallets, like plastic knives, sticks, or hammers. Just ensure you don’t damage the instrument.

 Concepts: sound decay, decay times, density, sonic frequency