Sound Experiments
Index Bouncing Sound Making a Stethoscope Pitch Switch Playing Pipes Seeing Sound Waves Shoebox Guitar Slinky Waves String Telephone Travel of Sound Through Various Phases of Matter
Tube Chimes Water Bottles Supply List References Children’s Literature Notes
Bouncing Sound
Index
Sounds travel at different speeds through solids, liquids, and gases, and they do not pass very well from one substance to another. So, if you shout at a brick wall, little of the sound energy will come out into the air on the other side. Instead, most of the sound waves bounce back off the wall. You will probably have noticed this when you hear an echo in a tunnel or an empty room. An echo is a reflected sound. Echoes can be useful or they can be a nuisance. Architects use their knowledge of how sound waves are reflected when they design buildings. A noisy restaurant can be made quieter by covering the floor, walls, and ceiling with soft or bumpy materials that soak up the sounds. But the walls and ceiling of a concert hall will be built from materials that reflect the sounds of the orchestra toward the audience. Even sound waves we cannot hear produce echoes that give us important information. Some vibrations with very high frequencies produce ultrasound. Ultrasound can travel through some solid objects and be reflected by others. An example is the use of ultrasound to “see” an unborn baby inside its mother’s womb. Another example is sonar, which stands for “Sound Navigation and Ranging” and is used by ships to study the seafloor.
Materials
1 clock or watch with a quiet tick 3 or 4 similar cardboard tubes Sound-reflecting and sound-absorbing materials (i.e. stiff cardboard, plastic, aluminum foil, ceramic tiles, cork, egg cartons, modeling clay, scissors)
What To Do
Arrange two cardboard tubes on a table so that they are at right angles to each other. Place the clock or watch at the end of one tube and put your ear close to the end of the other. Can you hear the tick of the clock? Now cut out a square of stiff cardboard and stand it upright in modeling clay supports. Place the cardboard tube where the open ends of the tubes come close together. Listen again for the tick of the clock. How does the loudness of the tick compare to the first test? Repeat the test with squares of the other materials. Next, try reflecting the sound of the ticking clock by using some of the other cardboard tubes and squares of the best sound reflecting material. How many times can you reflect the sound?
Questions
1. Which material is the best sound reflector? 2. What makes some materials good sound reflectors and other materials poor sound reflectors? 3. Think of some times when echoes may be useful and other times when echoes may be harmful.
Summary
When you talk into the cup, you cause it to vibrate. This in turn causes the string to vibrate, which causes the cup on the other end of the string to vibrate. Whoever is listening hears the vibrations caused by your voice after they have traveled through the cups and the string.
Source
“SOUND: Science Projects.” Simon de Pinna, Raintree Steck-Vaughn Publishers: Austin, 1998, p. 8-9. © S. Olesik, WOW Project, Ohio State University, 2000.
Making a Stethoscope
Index
Doctors use stethoscopes to listen to people’s heartbeats. As the heart beats, it causes the stethoscope to vibrate. These vibrations are transmitted as sound to the doctor’s ears. A stethoscope amplifies the sound (i.e. it increases the loudness of the sound) so the doctor can clearly hear the faint heartbeats.
Materials
2 plastic funnels 20 in. (50 cm) of flexible plastic tubing
What To Do
Push the narrow ends of two funnels into the open ends of the plastic tubing. If the tubing is too narrow, warm the ends near a source of heat to soften the plastic. Ask a friend to hold one funnel over his or her chest. Place the other funnel over your ear and listen carefully. Can you hear your friend’s heart beating?
Questions
1. How do you think your stethoscope works? 2. How is your apparatus like a real stethoscope? 3. Can you think of any other useful applications for this device?
Source
“SOUND: Science Activities.” Graham Peacock, Wayland Publishers, Ltd., 1993, p. 23. © S. Olesik, WOW Project, Ohio State University, 2000.
Pitch Switch
Index
Humans can hear a wide range of loudness, from the very quiet sounds of a whisper to the loud roar of a jet engine. We can also hear extremely small differences in the highness and lowness of sounds. This characteristic of sound is called pitch. Some musical instruments, such as a piano or harp, have strings, each of which plays a different pitch. The longer the string, the lower the pitch.
Materials
1 paper cup 1 push pin 1 long rubber band 1 paper clip 1 wooden ruler Tape Scissors
What To Do
Use the pushpin to carefully poke a hole in the center of the bottom of a cup. Cut a long rubber band. Thread one end through the hole in the cup. Tie two or three knots in the end of the rubber band so it will stay securely in the cup. Tape the cup to the ruler so that the bottom of the cup is on about the 2 cm line. Tie a paper clip to the free end of the rubber band. Stretch the rubber band to the other end of the ruler. Tape down the rubber band and hook one arm of the paper clip under the end of the ruler so the rubber band stays securely attached to the end of the ruler. Hold the open end of the cup to your ear. Pluck the rubber band once. Press the rubber band down onto the ruler near the end opposite the cup. Pluck the rubber band again. Press the rubber band down as you move your finger closer and closer to the cup. Pluck the rubber band each time you press down on the rubber band. Notice the difference in the sounds you hear when different parts of the rubber band are vibrating.
Questions
1. How was the sound different when you pressed the rubber band down to the ruler? 2. How does changing the length of the vibrating part of the rubber band change the pitch of the sound? 3. How do you think the sound will change if, instead of pressing the rubber band down closer and closer to the cup, you press the rubber band down further away from the cup? Try it! 4. How is question 3 similar to the way a guitar player can change the pitch of a string on a guitar?
Summary
Very rapid vibrations produce high pitch sounds and lower pitch sounds are the products of slower vibrations. The pitch switch is able to produce a variety pitches because the amount of the rubber band used to produce the sounds can be varied. When a long portion of the rubber band is plucked it vibrates slowly and a low sound is heard. When a shorter piece of the rubber band is plucked it vibrates more quickly and a higher note is heard. There is a difference in the speed of the vibrations when longer or shorter portions of the rubber band are plucked because of the difference in mass of the portions. A heavier piece of rubber band requires more force to make it vibrate, so it vibrates more slowly than a shorter piece would if plucked with the same force.
Source
“The Best of Wonders Science: Elementary Science Activities.” American Institute of Physics, Delmar Publishers: Albany, 1997, p. 455. © S. Olesik, WOW Project, Ohio State University, 2000.
Playing Pipes
Index
Many musical instruments have pipes. When air inside a pipe is vibrated, it produces a sound. The traditional organ is probably the best-known instrument that consists of columns of air, but other examples are found throughout the orchestra. They include wind instruments, such as recorders, oboes, and clarinets, and brass instruments, such as trumpets and trombones. In an organ, there are a number of hollow pipes; each one has a different length. When air is blown across the bottom end of a pipe, the air inside the pipe vibrates. The length of the pipe determines the note produced by the vibrating column of air. The shorter the pipe, the less air there is to vibrate and the higher the note. A long pipe contains a greater volume of air and vibrates more slowly, producing a lower note.
Materials
8 drinking straws Tape Scissors
What To Do
Cut 8 straws to different lengths. Blow across the top of each straw to hear the note it makes. Try to find lengths that give a wide range of notes from high to low. Tape the straws together so that they are level at one end. Try blowing across them to make an octave scale.
Questions
1. How is the length of the tube related to the pitch of the sound it creates? 2. Can you play a tune on your panpipes?
Summary
Very rapid vibrations produce high pitch sounds and lower pitch sounds are the products of slower vibrations. When a number of vibrations are initiated with approximately the same force the speed of the vibrations depends upon the amount of matter being vibrated. A greater amount of matter will vibrate more slowly than a lesser amount of matter when vibrated by the same amount of force. In the case of the panpipes it is the air inside the pipes that vibrates. The longer pipes have more air inside them, so when they are blown into the air vibrates slowly and produces a low note, compared to the shorter pipes. Test this by blowing equally hard into each of the pipes and listening to the difference in the sounds. Then, increase the rate of vibration by blowing twice as hard into each pipe. For each pipe a higher sound will be heard than when blowing without so much force.
Source
“SOUND: Science Projects.� Simon de Pinna, Raintree Steck-Vaughn Publishers: Austin, 1998, p. 32. Š S. Olesik, WOW Project, Ohio State University, 2000.
Seeing Sound Waves
Index
What can travel without being seen? What allows you to feel a loud noise? What sort of a wave looks more like a slinky than an ocean? SOUND WAVES!
Materials
1 large cake or cookie tin 1 sheet of plastic wrap 1 long rubber band 1 baking tray 1 wooden spoon Fine sand
What To Do
Make a drum by stretching a piece of plastic film over a large round tin. Stretch the rubber band around the tin to hold the plastic taut. Sprinkle a teaspoon of sand on to the top of the plastic drumskin. Hold a baking tray above your drum, and hit it sharply with a wooden spoon.
Questions
1. What did you observe? 2. What caused the sand to dance up and down on the drumskin?
Summary
You cannot see sound waves in the air, but you can see their effects. When you strike a baking tray, the metal continues to vibrate for a fraction of a second afterward. As it vibrates, the air around is also vibrated. These little vibrations in the air (sound waves) quickly work their way out through the air in all directions. When they hit the drumskin, they set that vibrating too, so the sand dances up and down on the drumskin. The sound waves that reach your ear make you hear the bang.
Source
“How Science Works.” Judith Hann, Dorling Kindersley Limited: London, 1991, p. 105. © S. Olesik, WOW Project, Ohio State University, 2000.
Shoebox Guitar
Index
Guitars are musical instruments that produce sounds when their strings are plucked. The guitar can produce a great variety of sounds since the six different strings can be plucked and strummed in innumerable ways. Simple guitars can be made from shoeboxes and rubber bands.
Materials
1 shoebox or other small cardboard box 4-5 rubber bands with different lengths and widths 8-10 metal paper fasteners Tape Pen
What To Do
Show students a sample shoebox guitar. Pluck the rubber bands one at a time to make different sounds. Let students work in groups of three or four to make guitars. On the lid of the box near the center trace a large circle. Carefully cut the cardboard to remove the circle from the lid. Keep the circle for the next step. Make a bridge for the guitar by folding the outer two thirds of the circle inwards so the edges touch. Tape the top edges together and tape the bridge onto the lid of the shoebox guitar. The bridge should be aligned so that it is near one end of the lid and the long part of the bridge is parallel to the short sides of the lid. Use the pen to make 4 or 5 evenly spaced holes along the each of the short sides of the shoebox lid. Push a paper fastener through each hole and secure them with the heads on the outside of the box lid. Stretch 4 to 5 rubber bands lengthwise across the lid, securing them by tying the ends to the paper fasteners. Stretch the rubber bands over the bridge. If necessary to help the rubber bands stay in place cut small notches in the top of the bridge for the rubber bands to nest in. Place the lid on the shoebox and try out the new guitar. Notice the different sounds that can be made by using rubber bands of various thicknesses or by tightening the rubber bands that are already attached.
Questions
1. How are the sounds being produced? 2. Why are the sounds of the various bands different?
Summary
Plucking the rubber bands on the shoebox guitar causes them to vibrate. This vibration in turn produces sounds. The pitch of the sound will vary depending on the thickness and length of the rubber band. In general, the thicker the rubber band, the lower the pitch and the longer the rubber band, the lower the pitch. This is because thick rubber bands have more mass than thin ones and long rubber have more mass than short ones. The higher the mass, the slower the rubber band will vibrate. Slow vibrations produce low pitches or frequencies, and fast vibrations produce high pitches or frequencies.
Source
“Teaching Physics with TOYS: Activities for Grades K-9.” Taylor, Poth, & Portman, Terrific Science Press: Middletown, 1995, p.89. © S. Olesik, WOW Project, Ohio State University, 2000.
Slinky Waves
Index
Both sound and light travel as waves, but sound waves behave in a different way than light waves. Light waves can move either up and down or from side to side. They are called transverse waves and they are the same type of waves as those you see on water. Sound waves, which are longitudinal waves, move back and forth in the direction that the sound is traveling.
Materials
1 long length of thin rope (6-8 ft.) 1 Slinky
What To Do
Tie one end of the length of rope around a post or door handle and hold the other end fairly tight. Shake your hand up and down to make a wave in the rope. This is a transverse wave, like a water wave or a light wave. Shake your hand faster and observe what happens. Stretch out the Slinky on a smooth floor and ask a friend to hold one end.Holding the other end, give it a sharp push toward your friend. Notice the wave of tight coils move along the Slinky. This is a longitudinal wave, like a sound wave.
Questions
1. When shaking the rope, what happens to the number of waves when you shake your hand faster? 2. When shaking the rope, what happens to the number of waves when you shake your hand farther from side to side or up and down? 3. What should you do to make waves in the Slinky of higher frequency and greater amplitude?
Summary
Sound waves move through the air with a squeezing and stretching of molecules of air. When a vibration is produced the air around the source of the vibration is pushed together tightly, then stretched out as the squeezed air molecules push away from each other. This motion continues and the longitudinal sound wave propagates through the air. If you watch the thin cone on the front of a loudspeaker you can see that the sounds make it bounce in and out. When the cone vibrates, it pushes and pulls the air in front of it, first squeezing the air as it pushes it and then stretching the air as the cone pulls back. If you put your hand in front of a working loudspeaker you can feel the air vibrating. When something causes an object to vibrate, the sound waves spread out as ripples of squeezed air in the same way that ripples of water spread out. The number of these highpressure waves per second is the frequency of the sound. The amount that the air is squeezed in each ripple is the amplitude of the sound. The greater the squeeze, the louder the sound.
Source
“SOUND: Science Projects.” Simon de Pinna, Raintree Steck-Vaughn Publishers: Austin, 1998, p. 8-9. © S. Olesik, WOW Project, Ohio State University, 2000.
String Telephone
Index
Besides traveling through air, sound can also travel through solid objects.
Materials
2 paper or plastic cups (empty yogurt containers work well) 1 piece of string about 2 meters long Scissors 1 pushpin 2 paperclips
What To Do
Poke a small hole in the bottom of each cup with the pushpin. Thread the string through the holes and tie a paperclip to each end of the string to ensure that it is secured inside the cup. Give one cup to a friend, and take the cups far apart, so that the string is tight. Talk and listen to each other through the string telephone.
Questions
1. What happens if the string hangs loose? 2. What happens if you hold the string? 3. What happens if you connect three or four string telephones together?
Summary
When you talk into the cup, you cause it to vibrate. This in turn causes the string to vibrate, which causes the cup on the other end of the string to vibrate. Whoever is listening hears the vibrations caused by your voice after they have traveled through the cups and the string.
Source
“SOUND: Science Activities.” Graham Peacock, Wayland Publishers, Ltd.: New York, 1993, p. 20-21. “Sound Science.” Etta Kaner, 1991, Addison-Wesley, New York, p. 88-89. “Sound.” K. L. Siepak, 1994, Carson-Dellosa Publishing Co., p. 31-32. © S. Olesik, WOW Project, Ohio State University, 2000.
Travel of Sound Through Various Phases of Matter
Index
To reach your ear, sound usually travels through the air. But sound can travel through other things too. Try the activity below to see how well sound travels through the different states of matter: solids, liquids, and gases.
Materials
3 zip-closing plastic bags Water Sand or dirt Wooden stick or spoon
What To Do
Put sand or dirt in a plastic bag so that it is about half full. Push the extra air out and then seal it so that no sand or dirt will leak out. Lay the bag on its side. Fill another plastic bag with water so that it is as full as the bag of dirt. Push the extra air out and then seal it so that no water will leak out. Lay the bag on its side. Blow into one of your plastic bags so that it is inflated. Let some air out until the bag is as full as the bags of dirt and water. Seal it so that no air will leak out. Lay the bag on its side. Clear off a table and place one of the bags on the table. Put one ear gently on the bag and put your finger in your other ear. Lightly tap or rub the table with the wooden stick from about an arm’s length away. How well can you hear the sound? Lift your ear off the bag and tap or rub the stick again. Do you hear it better with or without the bag? Repeat step 4 with the other two bags.
Questions
1. Through which bag did you hear the sound best? Through which bag was the sound hardest to hear? 2. People who lived on the Great Plains in the early days of the United States put an ear on the ground to tell if buffalo or horses were coming. Why didn’t they simply listen in the air? 3. Dolphins and whales communicate through great distances underwater. Do you think they could communicate from so far away if they lived on land?
Source
“The Best of Wonders Science: Elementary Science Activities.” American Institute of Physics, Delmar Publishers: Albany, NY, 1997, p. 456. © S. Olesik, WOW Project, Ohio State University, 2000.
Tube Chimes
Index
Percussion instruments produce sounds when they are struck, shaken, scraped, or crashed together. Some have a fixed note that cannot be changed, such as the triangle, cymbals, gong, or maracas. They are made from solid materials, usually metal or wood and, because the sounds they make do not involve vibrating columns of air, their sounds tend to be sharp and short-lived. Other percussion instruments, including the xylophone and tubular bells, are tuned to a particular pitch and can play octaves. A xylophone is also made from metal or wood - often a mixture of the two - and consists of a number of bars, arranged in a similar way to the keys on a piano. Each bar is made a specific length so that it produces a sound of a certain pitch. Short bars make high notes and longer bars make lower notes.
Materials
60” of copper tubing (any diameter) Broom handle Tape String Scissors 2 large nails Hacksaw
What To Do
Using the hacksaw cut a length of copper pipe into 8 pieces (4”, 5”, 6”, 7”, 8”, 9”, 10”, and 11”). Lay the broom handle across the backs of two chairs. Cut 8 similar pieces of string and tie the first to the broom handle. Take the shortest tube and use tape to attach the tube to the piece of string. Repeat this for the other tubes, trying to get them to hang straight and with their tops at the same height. Strike to tubes gently with a long nail to make them ring.
Questions
1. How does the length of the pipe relate to the pitch of the sound produced? 2. Can you make different sounds using objects other than the nails to strike the tubes?
Source
“SOUND: Science Projects.” Simon de Pinna, Raintree Steck-Vaughn Publishers: Austin, 1998, p. 36-37. © S. Olesik, WOW Project, Ohio State University, 2000.
Water Bottles (Resonance)
Index
All objects have a natural rate of vibration depending on their size and shape. When two objects have the same natural rate of vibration, one can make the other vibrate. If two guitars are tuned exactly the same, a string vibrating on one will cause the same string to vibrate on the other. The two instruments are said to be in resonance. Acoustics are the study of how sound waves behave and how they can be controlled. Acoustical engineers design auditoriums with a combination of soundabsorbing and sound-reflecting materials. In this manner, they can control echo and reverberation. Many auditoriums are also designed so that voices can be heard from the stage to the back of the room without artificial amplification.
Materials
2 identical glass bottles Disinfectant wipes
What To Do
Give pairs of students two glass bottles. Have one student hold the mouth of one of the bottles near his or her ear. Have the second student stand about 1 meter to one side of the first student and blow across the top of the other bottle until a clear note is produced. Let the students take turns listening to the resonating notes. Wipe the bottles with disinfectant wipes.
Questions
1. How does the bottle held near the student’s ear respond? 2. Name a part of the school where echoes are produced often. (e.g. gym, hallway) 3. Name a part of the school where sounds are more muffled. (e.g. carpeted classrooms)
Source
“Sound Fundamentals.” Robert W. Wood, Chelsea House Publishers: Philadelphia, 1999, p. 47-48. © S. Olesik, WOW Project, Ohio State University, 2000.
Index
Supply Lists Making a Stethoscope
2 plastic funnels 20 in. (50 cm) of flexible plastic tubing
Pitch Switch
1 paper cup 1 push pin 1 long rubber band 1 paper clip 1 wooden ruler Tape Scissors
Playing Pipes
8 drinking straws Tape Scissors
Seeing Sound Waves
1 large cake or cookie tin 1 sheet of plastic wrap 1 long rubber band 1 baking tray 1 wooden spoon Fine sand
Shoebox Guitar
1 shoebox or other small cardboard box 4-5 rubber bands with different lengths and widths 8-10 metal paper fasteners Tape Pen
Slinky Waves
1 long length of thin rope (6-8 ft.) 1 Slinky
String Telephone
2 paper or plastic cups (empty yogurt containers work well) 1 piece of string about 2 meters long Scissors 1 pushpin 2 paperclips
Travel of Sound Through Various Phases of Matter 3 zip-closing plastic bags Water Sand or dirt Wooden stick or spoon
Tube Chimes
60 inches of copper tubing (any diameter) Broom handle Tape String Scissors 2 large nails Hacksaw
Water Bottles (Resonance) 2 identical glass bottles Disinfectant wipes
References
Index
“The Best of Wonders Science: Elementary Science Activities.” American Institute of Physics, Delmar Publishers: Albany, 1997. “Teaching Physics with TOYS: Activities for Grades K-9.” Taylor, Poth, & Portman, Terrific Science Press: Middletown, 1995. “SOUND: Science Projects.” Simon de Pinna, Raintree Steck-Vaughn Publishers: Austin, 1998. “How Science Works.” Judith Hann, Dorling Kindersley Limited: London, 1991. “SOUND: Science Activities.” Graham Peacock, Wayland Publishers, Ltd., 1993. “Sound Fundamentals.” Robert W. Wood, Chelsea House Publishers: Philadelphia, 1999. “Sound Science.” Etta Kaner, 1991, Addison-Wesley, New York. “Sound.” K. L. Siepak, 1994, Carson-Dellosa Publishing Co.
Children’s Literature
Index
“The Magic School Bus in the Haunted Museum: A Book About Sound.” By Linda Beech, illustrated by Joel Schick. Book adaptation of an episode of the animated TV series The Magic School Bus, based on the series by Joanna Cole and Bruce Degan. Scholastic, Inc.: New York, 1995. ISBN 0-590-48412-5. “Hearing Sounds With Easy-to-Make Scientific Projects.” By Gary Gibson, illustrated by Tony Kenyon. Copper Beech Books: Brookfield, 1995. ISBN 1-56294-614-5. “The Usborne Internet-Linked Library of Science: Light, Sound & Electricity.” By Kirsteen Rogers, Phillip Clarke, Alastair Smith, and Corinne Henderson. Usborne Publishing Ltd.: London, 2001. “Fascinating Science Projects: Sound.” By Bobbi Searle. Copper Beech Books: Brookfield, 2002. ISBN 0-7613-1737-6. “The Listening Walk.” By Paul Showers, illustrated by Aliki Brandenberg. HarperCollins Publishers: New York, 1991. ISBN 0-06-021638-7. “Sound and Light.” By Robert Snedden. Reed Educational & Professional Publishing: Hong Kong, 1999. ISBN 1-57572-870-2. “The Usborne Illustrated Encyclopedia: Science and Technology.” Usborne Publishing: London, 1996. “Sound and Music.” By Alan Ward. Franklin Watts, Inc.: New York, 1992. ISBN 0-513-14237-X.
Notes
Index
There are currently no notes on this unit. If you have suggestions or changes to make on the experiments or units, please email us! Our address is wow@chemistry.ohio-state.edu. Š S. Olesik, WOW Project, Ohio State University, 2002.
Copyright Š 2002-2010 by S.Olesik, Wonders of Our World Project (WOW), the Ohio State University. Permission to make digital or hard copies of portions of this work for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page in print or the first screen in digital media. Abstracting with credit is permitted.