In this activity, you will explore methods for visualizing sound and then create a device to amplify the sounds generated from a cell phone or tablet by utilizing Google’s Science Journal app.
Clear drinking glasses
- Tuning forks
- Crisped rice cereal
- Toilet paper rolls
- Small Mylar sheets (the size of a small index card is sufficient)
- Coffee Canisters
- Laser pointers
- Paper towels
- Rubber bands
Investigation #1: Seeing Sound Waves
- Fill a drinking glass or clear container with water.
- Strike the side of the table gently with the tuning fork.
- Look at the tips of the tuning fork after you strike it. What do you see, hear or feel?
- Make the tuning fork vibrate.
- Once the tuning fork vibrates, place it gently in the water. What happens to the water? Are there different effects if the tuning fork comes close to the water but doesn’t touch the water?
Sounds are vibrations that move through matter. When a tuning fork is struck, you cannot see the sound waves move out from the tuning fork, but you can hear them. When the tuning fork vibrates, air molecules quickly bounce off the fork. The vibrations move through the air until they reach your ear, causing it to hear a sound. The vibration of air molecules is invisible to us. However, we can witness this vibration if it occurs in a denser medium such as water.
Investigation #2: Crisped Rice Cereal Dance
- Place half a teaspoon of crisped rice cereal in an empty balloon.
- Gently blow up the balloon and tie it securely.
- Strike your tuning fork to create vibrations and place the tuning fork on the balloon where the cereal is resting in the balloon (usually at the bottom). Predict what will happen and then compare your predictions with your observations.
The vibrations from the tuning fork cause the balloon to vibrate which causes the cereal to move around in the balloon.
Investigation #3: Seeing Sound Tube
- Gather a balloon, a small sheet of Mylar, a rubber band, the scissors and the laser.
- Cut the top of the balloon off, leaving the rounded part intact.
- Place the balloon firmly on the toilet paper tube so the balloon is stretched as far as it can go.
- Reinforce the balloon with the rubber band to keep it in place.
- Cut three or four 1/2-inch-squares of Mylar and tape them onto the balloon surface.
- Ask a partner to shine the laser onto the Mylar while the tube is aimed downward at an angle. The reflection of the laser should hit the table.
- Cup your hand over the tube and place your mouth on your cupped hand. Talk into the tube. What do you observe? What happens when you change the pitch of your voice?
The vibration from your voice travels into the tube and hits the inner surface of the balloon, which vibrates the balloon and the Mylar, creating different shapes in the projected laser image on the table. Changes in pitch will create changes in the laser image.
What can we say about sound based on our experiments?
When something moves quickly back and forth, it is vibrating. You hear a sound when a moving object makes the air vibrate. These vibrations are called sound waves and can travel through any substance, whether it is a solid (like metal), a liquid (like water), or a gas (like air), but the speed at which sound waves travel is different in each substance. Substances are made up of molecules. The more tightly “packed” the molecules are, such as in solid objects, the quicker the sound waves can travel. More loosely “packed” molecules (like air), cause the waves to move more slowly. Sound waves travel the fastest through solids, followed by water, and then air.
Vibrations also create different notes or pitches. High-pitched sounds, such as the sound of a whistle, create waves that are close together. Lower-pitched sounds, like thunder, create waves that are farther apart. The pitch of a sound is determined by its frequency. Frequency is the number of waves that pass a point in one second. The higher the frequency, the higher the pitch. The lower the frequency, the lower the pitch. The length of a vibrating object contributes to the pitch.
WHAT’S NEXT? TURN IT UP!
Make A Better Speaker Challenge
In this design engineering activity, you will amplify the sounds coming from a device of your choice by using simple, everyday materials.
First, gather recyclable materials. We suggest the following:
- Portable music player or cell phone, or tablet
- Cups (plastic or foam)
- Various types of paper
- Toilet paper rolls or paper towel rolls
- Plastic bottles
- Cardboard boxes
- Cell phone or tablet with the Google Science Journal app
Create a speaker that will amplify the sound coming from your mobile device. You can use any of the materials in a way that you think will amplify the sound. Then use the Google Science Journal app to measure if your design increased the sound waves emitted from your device.
Step 1. Investigate the materials available to create your design. What are they made of and how can you arrange them so that they will amplify sound?
Step 2. Create an initial sketch of what you would like to make, label the parts, or describe your idea.
Step 3. Start making your speaker and attach it to your mobile device. This is your prototype!
Step 4. Turn the device on and use the Google Science Journal app to measure the decibel output of your design. Compare it to the decibel output of your phone without your prototype attached to it. Did it improve the sound?
Step 5. The best designs are always based on a previous design that failed in some way. Reiterate your design to try to make it even better.
Sounds can be made louder or amplified in a number of ways. By providing more energy in making the sound, its loudness can be increased. This could be achieved by beating a drum with greater vigor, blowing harder on the recorder, or using more energy when shouting. Electricity can supply the extra energy needed to increase the volume of sound, for instance in a hi-fi amplifier. When a stylus rests in the grooves of a rotating vinyl record, it is made to vibrate with very small movements. These movements are turned into small electrical impulses and sent to the amplifier of the hi-fi system. Here the small electrical currents are made larger and sent to the loudspeaker system where they are converted into the much larger vibrations of the speaker cone. A microphone picks up the small vibrations from the voice in a similar way. The tiny movements inside the microphone of a coil of wire inside a strong magnet can be turned into small electrical impulses. These once more can be amplified by an electronic system and made to drive a loudspeaker.
Funneling sound waves into the ear can also increase the volume of sound we hear. The outer ear already provides a funneling effect but a hearing trumpet will improve this. Holding our hands behind our ears will also have an impressive effect on the volume of sound received.
Another way in which sounds can be amplified is seen on the acoustic guitar, violin, drum, xylophone and many other instruments. These types of instruments are basically hollow sound boxes made of rigid material and often with a hole in. The small sound made by the instrument enables the sound box to reverberate and thus to project the sound further away from the instrument.
While there are many ways to create a speaker using the materials listed above, the following is a step-by-step detail of one possible way to do so.
Figure 1: Gather the materials you’ve chosen to use. Pictured is a cell phone, 2 cups, a toilet paper roll, a ruler, a pen and a precision blade.
Figure 2: Measure and mark the center of the toilet paper roll.
Figure 3: Since the built-in speaker on the phone is on the bottom, it was necessary to trace the shape of the bottom of the phone to prepare for cutting.
Figure 4: Cut the traced shape out of your toilet paper roll cutting an extra 1/8 inch to create flaps at the ends as pictured below.
Figure 5: Trace the shape of the toilet paper roll onto the side of each cup to prepare for cutting.
Figure 6: Try to make the holes in both cups identical.
Figure 7: Fit either end of your toilet paper roll into the holes in the cups.
Figure 8: Arrange the phone so that it points upward and the top of the cups face the direction you want the sound to be the loudest.
See if you can come up with a different way to amplify the sounds from your device using simple materials.
Making a Better Speaker activity is made possible with support from Making & Science, an initiative of Google.