Listening to Sounds Lab

Purpose:
To determine a way to amplify sound traveling to your ear.

Procedure:
1. Tie 2 strings to the handle of a metal spoon. Each string should be about 40 cm long.
2. Hold one end of each string in each hand. Bump the bowl of the spoon against a desk or other hard, solid object. Listen to the sound.
3. Now wrap the ends of the string around your fingers.
4. Put your index fingers up against your ears and bump the spoon against the object again.

Conclusion:

1. How does the first sound compare with the sound you heard with your fingers up against your ears? The vibration was stronger and it sounded louder and deeper on the second sound test than with the first one.

2. How did the sound travel to your ears when you had the string touching your ears? The vibration traveled through the string.

3. Why do you think it was easier to hear the sound when you put the strings by your ears? Because we were tightening the strings making it denser.

Section 2: Properties of Sound; Reflection

In this section I learn't about how:

• How a sound wave of greater intensity sounds louder (loudness = measured in decibels.)
  
• The pitch of a sound that you hear depends on the frequency of the wave/sound wave.
  
• And lastly, As the sound source of the wave moves toward the listener, the wave reach the listener with a higher frequency. The pitch appears to increase because of the Doppler effect. (E.G. ambulance.)

The main focuses in this unit were; the intensity and loudness of waves, the frequency and pitch of the waves, and the Doppler effects. All in all what i found most interesting in this section was learning about the Doppler effects because i have heard briefly about it before but never understood it in detail.

Section 1: The Nature of Sound; Reflection

In this chapter I learn't about sound and longitudinal waves, the speed of sound, and things that move faster than sound.
I learn't that, wound is a disturbance that travels through a variety of different mediums in the form of longitudinal waves. Also that the speed that sound travels depends on the elasticity, density, and the temperature that the medium is. I also learn't about how my voice box and ear drum work as well as my vocal chords. Sounds can also travel through solids and liquids. I also thought that it was interesting about how the speed of sound is effected by how close together the particles in the medium/substance are.
Over all i think that the most interesting thing that i learn't about the nature of sound is that when sound hits a barrier with even the tiniest hole the waves will still pass through the hole!

Producing Sound: Rubber Bands

Procedure:

Have 2 partners hold each end of rubbber band and pull until the rubber band is tight.
pull the rubber band about 1 cm away from the middle. Let go. How far does the band move? It vibrates.
reapeat step 2 four times. each time, pull the band back further. Describe how the sound changes each time in the chart below.
Experiment: Frequency:
Have 2 partners each hold one end of the thicker rubber band and pull until the rubber band is tight.
pull the rubber band about 2cm away from the middle. Let it go. Observe the sound
repeat steps 1-2 with the thin rubber band and describe the difference in the chart below.
now, take the thicker rubber band again. Repeat steps 1-2.
Now pull the thicker rubber band again. Observe how the sound changes.
Last experiment:
Have 2 partners hole the thick rubber band just like in step 1.
Now, have one of your partners move his or her hand so that the rubber band is a little bit shorter.
Repeat step 8 two more times, making the rubber band a little shorter each time. Record your observations of the change in sound.
Results:
Experiment 1:

Distance away from middle	Description of sound
1cm	Low sounding
2cm	Getting slightly higher
3cm	Getting harder to pull
4cm	Higher and can hear vibration
5cm	Highest sounding and tangy sounding

Experiment 2:

Thickness of Rubber Band	Description of Sound
Thick	Deep and stiff sounding
Thin	Sound a lot higher and sounds slightly twangy

Tightness of Rubber Band	Description of Sound
Loose	Very low sounding
Tight	Medium sounding (slightly higher)
Tightest	A lot higher

Length of Rubber Band	Description of Sound
Longest	Low and stiff sounding
Long	High and twangy (can hear slight vibration)
Shortest	High sounding and can hear vibration clearly

Conclusion:
How did the sound change when you changed the amplitude (how far the rubber band was away from the middle point?)
It was harder to pull the rubber band back and it sounded stiffer, it was also easier to hear the vibration of the rubber band.
What happened when you changed the thickness, length, and tightness of the rubber band?
The longer the rubber band the lower and stiffer it would sound. The tighter the rubber band string was the higher the pitch would be, and the thicker the deeper sounding the rubber band was.

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 turn the guitar by TIGHTENING the strings (using the knobs on the guitar.)