Tuning Fork Lab

GUIDING QUESTION:

How does density of various solids affect the way the sound waves travel from the turning fork?

HYPOTHESIS:  

I think that sound from the tuning fork will travel best in metal, because I think that metal is the most dense of all the materials we are testing the tuning fork with.  This means that the sound will be louder and clearer, because there won’t be so much space between molecules/particles in the metal for the sound to travel through.

Control=Force, Tuning fork, Frequency, Length, Temperature (Loudness change)

Manipulated=Materials, Temperature

Responding=Pitch, Loudness, How long the sound lasts (Properties of sound)

EXPLORATION:

Materials:

Tuning Fork

Metal

Plastic

Wood

Paper

Notebook

Pencil (To record)

Procedure:

1. Find and gather the densities of following materials below.

2. Use a tuning fork, hit it against a manipulated variable.

3. After banging towards the object, place the small part or the edge of the tuning fork towards your ear.

4. Record the vibrations and the loudness of the manipulated variable.

5. Use this method to find the loudness of the other materials.

Data Tables:

Tuning Fork: 512C

Weight: 27.3g

	Metal	Wood	Plastic	Paper
Density	7.85g/cm3	5kg/cm3	7.85g/ml3	0.78g/cm3
Loudness	Can be expressed as very loud	(Ultra) VERY Loud, and its vibration lasts very long.	Bit loud, Bit soft - it is hard to determine	Very Soft; can’t hear that much
Other Observations	Measured on the metal attached to the board. The sound of the metal has caused disturbances to the classmates next to me (vibrations last for a long time.)	Measured on a wooden chair Could have similar frequency with metal	The plastic containing no materials didn’t vibrate that long due to the manufacture quality  (plus, the loudness might vary on the quality of the plastic)	The paper lasted only about 1 sec, the vibration lasted very short. Maybe the heavier the manipulated variable, vibration last longer
Vibration (Time Lasting) 3 Trials	10 Sec 8 Sec 8 Sec	11 Sec 10 Sec 8 Sec	4 Sec 4 Sec 3 Sec	2 Sec 1 Sec 1 Sec

Analysis of Data:

The table above shows that metal and wood are very similar in transmitting sound from place to place.  They are both pretty efficient, as they were pretty loud and the sound lasted for a very long time.  Wood might be a little better for listening to tuning forks, though, because the sound lasts a few seconds longer than on metal.  

 

Conclusion: 

My hypothesis was incorrect.  I believed that metal would be the best substance for listening to sound from the tuning fork, but I was wrong.  It was really wood that was the best sound transmitter.  This makes sense, because after we discovered the densities of each material, we found out that wood is more dense than metal.  There might have been some error in how we recorded the density of each material.  We looked them up on the internet, and we discovered that each type of metal, wood, plastic, and even paper, has a different density (steel and aluminum are different, oak wood and maple wood are different, etc.)  We weren’t sure which metal, plastic, or wood we were using, so we just picked the option that made the most sense.  Unfortunately, we had/have no way of telling whether or not what we thought made sense is actually true, so there is a big possibility there is error there.  

Further Inquiry:   

If I were to do this project again, I would also include hollow objects.  When testing the tuning fork and the sound it produced on metal, wood, paper, and plastic, we rarely used something that was hollow.  The chair is not hollow, paper is not hollow, plastic is not hollow, and metal isn’t either.  I have my own tuning fork at home that I use to tune my violin, and I always place it on the body of my instrument to hear the sound.  Usually, it is clear, loud, and easy to hear:  I can hear it well without placing my ear on the instrument.  This might be because since a violin is hollow, there is more room for the sound to reverberate and echo.  This may double or triple how loud the tuning fork is.  Next time, we should do wood, hollow wood, metal, hollow metal, plastic, hollow plastic, and paper.    

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 the 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 first sound is a pretty loud sound with a big "twang," whereas the second sound is slightly louder, and it has a more resonating quality to it.  Also, it is accompanied with a subtle hum.

2.)  How did the sound travel to your ears when you had the string touching your ears?

The sound traveled to our ears through longitudinal waves on the string.

3.)  Why do you think it was easier to hear the sound when you put the strings by your ears?

I think it was easier for us to hear the sound through the string, because the sound traveled through it, which brought it directly to our ears, instead of us having our ears searching for it.

Reflection on Properties of Sound

Sound Wave

          I thought that this chapter was very interesting.  We learned about intensity, loudness, frequency, pitch, and the Doppler effect.  Intensity is the amount of energy a sound wave carries - the more energy there is, the more the molecules of the medium move.  Intensity is measured in watts per meters squared.  Loudness is what you actually hear.  A sound wave of greater intensity sounds louder, whereas a sound wave with less intensity sounds softer.  Loudness is measured in decibels.  For every ten decibels, the amount of sound you have is ten times louder.  For example, 20 dB is 10 times as loud as 30 dB.  The textbook had some examples:  rustling leaves are 10 dB, a whisper is 20 dB, soft music is 30 dB, the average classroom is 35 dB, the average home is 40-50 dB, and a loud conversation is around 60-70 dB.  Frequency is the amount of vibrations per second a sound wave creates.  The higher the frequency, the higher the sound.  Sometimes, the frequency of a sound is either too high or too low for the human ear to detect it.  This is called either ultrasound (high) or infrasound (below).  Pitch is a description of how high or low a sound seems to a person.  It depends on the frequency of a sound wave, so the higher the frequency, the higher the pitch, and vice-versa.  When using a string instrument, the pitch depends on the length, tightness, thickness, and material of the string.  You can change the pitch by changing the properties of the string that produces it - you can tighten it and make it higher.  Lastly, the Doppler effect is what happens when you hear a siren from an ambulance or a police car go by.  When the car is behind you, the siren seems softer, when it's right in front of you, it seems loud, and when it has passed you, it seems quiet again.  This is because as the car approaches you, the sound waves come toward you more quickly, but once it's passed, the sound waves come to you more and more slowly, so they don't seem as loud to you anymore.

Doppler Effect

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? Not very far.  Describe the sound you hear in the table below.
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 hold the thick rubber band just like in step 1.  Repeat step 2 and observe 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. 

Conclusion: 
1.) How did the sound change when you changed the amplitude (how far the rubber band was away from the middle point)?
When we changed the amplitude of the rubber band, the pitch became slightly higher and better quality when the middle was farther away.
2.)  What happened when you changed the thickness, length, and tightness of the rubber band?
When we changed the thickness, the type of sound changed, when we changed the length of the rubber band, the pitch went up, and when we changed the tightness, the volume went up. 
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?
Sally could tune her guitar by turning the peg of the flat string to make it tighter and shorter. 

How People Produce Sound Lab

Objective:  
-observe how your vocal cords affect the sounds you make
-observe how your lips, tongue, and teeth influence the sounds you make

Procedure:
1.)  Pronounce the words in the list below to your partner.   Pay attention to how you pronounce the first letter of each word.
2.)  Together decide if you are stopping your breath when you are pronouncing the first letter of each word.  Use a check mark to record in the Data and Observations section if the consonant is stopped or open.

 My partner and I filled in the chart to the right with our decisions.

Conclusions:
1.) Is the shape of your mouth or the positon of your teeth or tongue different when you pronounce a "d" than when you pronounce a "t"?   
Yes, because when you pronounce a "d", you kind of flick your tongue off the roof of your mouth, whereas when you pronounce a "t", you bring your tongue right up to the base of your teeth - the part where your upper incisors meet with your gums. 

2.)  What is the difference between the sound of a "d" and the sound of a "v"?  
The difference between the sound of a "d" and the sound of a "v" lies with the way your mouth makes the sound.  With "d", your tongue goes to the roof of your mouth, whereas "v" is caused by your mouth moving together with your incisors flicking off your lower lip.  "D" creates a more solid sound, and "v" makes a sound that is less substantial.

3.)  For which first-letter sound(s) in the table do you use your lips and your voice but not your tongue or your teeth?  
We decided that we use our lips and voice for "b", "k", "p", and "g", but not for any other letters on the list.

4.)  What part of the larynx is like the strings of a guitar?

The vocal cords of the larynx are like the strings of a guitar.  When you talk, the vocal cords are forced together, and air is pushed between them.  This causes them to vibrate, just like guitar strings do when you pluck them.  This causes sound.

5)  Why do women usually have voices of higher pitches then men?
Women usually have higher voices then men, because as men grow older, their larynx grows more than women.  This makes the vocal cords grow thicker, which makes the voice deeper.  Also, cavities in the nose and back of the throat grow deeper, which allows their voices to reverberate and echo more. 


6.)  Why, then, are the voices of young girls and boys of about the same pitch?
Voices of young girls and boys are about the same pitch, because both genders haven't developed yet.  This means that the little boys wouldn't have had the chance to grow thicker vocal cords and deeper cavities. 


7.)  Do some research on what happens to your voice and your larynx when you get laryngitis.  Write a short summary about what you found out.
When you get laryngitis, it means that your voice box has been irritated or inflamed, which can cause you to have a very hoarse, deep, or lost voice, as well as a difficulty with swallowing, a sore throat, and a cough.  Laryngitis only lasts a few weeks, but there are some cases of chronic laryngitis that have lasting symptoms.  This illness can be caused by colds, the flu, smoking, allergies, or anything else that can agitate the voicebox such as a voice overuse (singing, shouting during sports, etc.).