Properties of Sound Lab

Purpose:

To determine how changing amplitude and frequency can change how a sound is perceived.

Procedure:

Experiment #1: Amplitude

1. Have 2 partners each hold one end of the thicker rubber band and pull until the rubber band is taut (not loose).

2. Pull the rubber band about 1 cm away from the middle. Let it go. How far does the band move? Describe the sound you hear in a table.

3. Repeat step 2 four more times. Each time, pull the band back further. Describe how the sound changes each time in the chart below.

Experiment #2: Frequency

1. Have 2 partners each hold one end of the thicker rubber band and pull until the rubber band is taut (not loose).

2. Pull the rubber band about 2 cm away from the middle. Let it go. Observe the sound.

3. Repeat steps 1-2 with the thin rubber band and describe the difference in the chart below.

4. Now, take the thicker rubber band again. Repeat steps 1-2.

5. Now pull the thicker rubber band a little bit tighter and repeat steps 1-2. Observe how the sound changes.

6. Pull the rubber band even tighter and repeat steps 1-2. Observe how the sound changes. Record your observations in the chart.

7. Last experiment: have two partners hold the thick rubber band just like in step 1. Repeat step 2 and observe the sound.

8. Now, have one of your partners move his or her hand so that the rubber band is a little bit shorter. Repeat step 2 and observe the change in the sound.

9. Repeat step 8 two more times, making the rubber band a little shorter each time. Record your observations of the change in sound.

Experiment #1

Experiment #2

CONCLUSION:

1. How did the sound change when you changed the amplitude (how far the rubber band was away from the middle point)?

The farther away you pulled it, the louder and sharper the sound became.

2. What happened when you changed the thickness, length, and tightness of the rubber band?

Thickness: the thicker the band is, the duller the sound

Tightness: the tighter the band is, the higher the pitch

Length: the shorter the band is, the higher the pitch

3. Sally is playing the guitar and notices that one of her strings is flat (pitch is too low). What can she do to fix this?

She can tighten the string, which will make the pitch higher.