We live in a big ball full of sounds. Here, there are few small experiment to propose at school to intoduce the subject.
EGGS AND PAPER
2 different projects to help demonstrate some of the physics of sound:
MATERIALS
1) 12 plastic 'Easter' eggs, small items such as rice, paper clips, marbles, pennies, etc.
2) Toilet paper roll cardboard inner tube, wax paper, rubber band.
INSTRUCTIONS
Have one person fill each of the plastic eggs with a different item. Put some rice in one, some dried beans in another, etc. Keep track of what you put in each egg by writing numbers on the egg. Have a different person try to see if they can figure out what is inside each egg by shaking and listening to the sound generated. After taking a first guess, now show the person the list of what items are in each egg and have them guess again. See if the person changes their mind about some of the previous guesses. Now open the eggs and see how close the guesses were to what was actually inside each egg.
Now, let's make a musical instrument called a kazoo. Cut a small square of wax paper about one inch larger than the end of the cardboard tube. After doing that, wrap the wax paper over one of the ends of the tube and put a rubber band over the paper to hold it in place. Now, put the open end of your kazoo up to your mouth and hum a tune into it. Notice how the the kazoo buzzes and vibrates to amplify (make louder) the sound of your voice.
What's going on?
Sound is created when the air around us gets pushed quickly (compressed) and then the push stops. This air compression produces what scientists call a sound wave. Our ears can detect that wave and through the ear's eardrum, some small bones, and some nerves, and tells our brain that a sound was just heard. Our brain can determine quickly all kinds of different sounds. Notice how just very small differences in the sound that came from the plastic eggs was just enough for you to figure out what was in each egg.
The sound of our voice seems to be made louder by humming into the kazoo because the kazoo resonates or vibrates with the sound of your voice. Your voice is a complex sound wave that contains lots of different sounds all put together so that it sounds like one sound. Scientists call the different sounds harmonics, and all those harmonics together is what makes your voice sound different than someone else's. As your voice travels down the cardboard tube and reaches the wax paper, the wax paper vibrates and all those harmonics get amplified (made louder). Not all the harmonics get amplified the same amount, so the kazoo actually changes the way your voice actually sounds. When you hum a tune into the kazoo, you get a completely different sound. Some people call this music, some call this noise.
Things to Remember
Sound is just air that has been compressed in 'waves'. Our ears are especially good at detecting those waves (also called listening). When we hear something, our brain is able to figure out in less than a second, whether we have heard this sound before, and if not, make really good guesses at what the sound came from. Think about how we are able to do this.
We, as humans, have created many more sounds. Some of these sounds are what we would call music and the music is created in lots of different ways. Many hundreds of years ago, people found that certain things, such as a metal wire, when plucked, produced a pleasant sound. Over the years the people created many musical instruments from that simple sound. Many other musical instruments came directly from what saw and heard around them. People observed nature and learned to imitate the sound they heard. See if you can think of some musical instruments that sound like the sounds of nature.
SEEING SOUND
Can you see sound? What is sound? Try this experiment and you'll have found a way to see sound.
MATERIALS
shoe box
elastic bands
extra cardboard - optional
INSTRUCTIONS
Tie a piece of thread to some tissue paper.
Put on some loud music and hold the thread in front of a loud speaker.
Watch what happens.
Try different types of music and see what happens.
Now try changing the volume.
What Should Happen
RESULTS
The sound vibrations should make the tissue paper shake.
METAL HANGER
MATERIALS
metal coat hanger
string
bowl of water
metal spoon
table
INSTRUCTIONS
Tie the ends of a piece of string to each corner of a metal coat hanger.
Then loop one end of the string around one index finger and the other end around the other index finger.
Put your fingers in your ears and bang the hanger against a table.
The sound waves from the vibrating hanger travel through the string and into your ear.
Do the same thing with a metal spoon.
RESULTS
Now try experimenting. Different materials vibrate differently. See if you can hear a difference in the way a muffin tin sounds. What do you think will happen? Make a prediction. Then change one thing-that's the variable-and test it out. Be sure to tell us what you thought was going to happen and what actually did happen. When you're done, send your reports to our special feedback area. Every week we'll post new results from ZOOMers' Stereo Hanger experiments.
STRING TELEPHONE
MATERIALS
two plastic cups
some string
paper clips
sharpened pencil for poking holes
INSTRUCTIONS
With the pencil, carefully poke a small hole in the bottom of each plastic cup.
Tie the paper clip to one end of the string.
Thread the other end of the string through the hole in the bottom of one of the cups. Be sure to thread it from the inside of the cup. The paperclip will keep the string from going all the way through the hole.
Then thread the string through the hole in the second cup, but this time do it from the outside of the cup.
Tie the second paper clip to the other end of the string. The paper clip should be inside the cup, just like the first paper clip.
Then, pull the cups so that the string is tight and have one person talk into the cup while the other person holds the cup to their ear.
Now it is time for you to experiment. Think of a question you want answered. Like, what is the farthest distance you can get the telephone to work using string? Would the sound go farther if you used empty soup cans instead of plastic cups? What about using two different sized cups? Make a prediction. Then change one thing-that's the variable-and test it out. Be sure to tell us what you thought was going to happen and what actually did happen. When you're done, send your reports to our special feedback area. Every week we'll post new results from ZOOMers' string telephone experiments.
SUPERSOUNDING DRUM
Be a sound scientist with the Super Sounding Drum.
MATERIALS
containers of different sizes
clear plastic shrink wrap that's used to insulate windows. It comes with double stick tape and you can get it at a hardware store.
you can also use regular plastic wrap.
masking tape
blow dryer
INSTRUCTIONS
First get a container that you think will make a good drum, like a metal bowl or an oatmeal container. Sylvia says that larger containers make better sounds.
Put the double-sided tape all the way around the container 2 inches from the top.
Cut 2 pieces of shrink wrap big enough to cover the tape on the container. Then, push it onto the tape.
Tape the edges of the shrink wrap with masking tape so it's really secure.
Now blow dry the shrink wrap with a blow dryer set on hot. This shrinks the plastic and makes a very tight drum.
Be sure you don't put the end of the blow dryer to close to the plastic, or it will melt.
Once it's really tight, bang your drum.
Now it's time to experiment. Try to change the sound your drum makes. Can you make a drum with a really deep sound? Test it out with different containers and then send your reports to our special feedback area. Be sure to tell us what materials you used and anything you learned from your experiments. Share your results with the world, right here at ZOOM!
MORE EXPERIMENTS.. http://www.hunkinsexperiments.com/themes/themes_sound.htm
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