Properties of Sound Lab

PROPERTIES OF SOUND LAB

Hypothesis: How does changing the amplitude and frequency 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 it taut (not loose).
2. Pull the rubber band about 1 cm away from the middle. Let it go. How far does the band move? It moves quite quickly back and forth not very far. Describe the sound you hear in the table below.
3. Repeat step 2 four 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 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 even 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 sound.
9. Repeat step 8 2 more times, making the rubber band a little shorter each time. Record your observations of the change in sound.

Result:

Experiment #1

Distance away from middle	Description of sound
1 cm	Low sound
2 cm	Gets higher
3 cm	Higher
4 cm	Higher
5 cm	Highest

Experiment #2

Thickness of the Rubber Band	Description of Sound
Thick	Deep sound ( Quite hard to pull)
Thin	Higher ( Almost a twangy sound)

Tightness of Rubber Band	Description of Sound
Loose	Low
Tight	Sort of Higher
Tightest	Quite a lot higher

Length of Rubber Band	Description of Sound
Longest	Pretty low and quite hard to tug
Long	Pretty high and quite twangy
Shortest	Highest you can almost hear vibration

Conclusion:

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

The sound changed because as the amplitude increased the sound became so much more twangy and higher in sound.

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

The tightness of the rubber band makes the sound much higher, the thickness of the rubber band makes it much harder to pull than a thin rubber band, and the length of the rubber band effects the sound making it lower or higher.

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?

Well what Sally can do is to tune her guitar. Turning the pegs on the top of a guitar one way will make them looser and another way will make them tighter. If she turns the pegs to make the strings tighter this will increase the pitch and making it higher.