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Physical Science by Timothy Sandow Genre Nonfiction Comprehension Skill Compare and Contrast Text Features • • • • Captions Labels Diagram Glossary Science Content Sound Scott Foresman Science 3.14 ISBN 0-328-13847-9 ì<(sk$m)=bdieha< +^-Ä-U-Ä-U Vocabulary What did you learn? compression wave 1. How is sound made? pitch 2. Describe the two ways stringed instruments are played. vibration Sound by Timothy Sandow 3. Explain how your ears help you hear. Illustrations: 7, 14 Jeff Mangiat Photographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd) Opener: ©Jake Rajs/Getty Images; Title Page: ©DK Images; ©Lynn Stone/Index Stock Imagery; 2 ©Joseph Sohm/ChromoSohm Inc./Corbis; 4 (CL, BR) ©DK Images; 5 Getty Images; 6 Getty Images, 8 Getty Images; 9 (CL, CC, BL) Getty Images; 11 ©Robert Brenner/PhotoEdit; 12 ©P. Freytag/Zefa/ Masterfile Corporation; 13 ©Scott Tysick/Masterfile Corporation; 15 (CL) ©Mark Tomalty/Masterfile Corporation, (CC) ©Christiana Carvalho-Frank Lane Picture Agency/Corbis, (BR) ©DK Images, (BL) Stone/Getty Images ISBN: 0-328-13847-9 Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05 4. In this book you have read about vocal cords and the pitch of your voice. Write to explain how their relationship works. Use details from the book. 5. Compare and Contrast How do people make sounds? How do animals make sounds? Compare and contrast the ways people and animals make sounds. What causes sounds? Take a walk in the city. Cities are noisy. Car horns honk. Buses and garbage trucks roar by. People talk Sounds are everywhere. Some sounds you hear may hurt your ears. You may like other sounds. Each sound you hear is different. Sounds are also alike in some ways. on the street. It is much quieter in the country. Birds chirp. Cows moo. Water trickles in a creek. Noisemakers are sometimes used on New Year’s Eve. Do you like the sounds they make? 2 3 The Causes of Sound Sound happens when matter moves back and forth Hitting or Plucking to Make Sound Some instruments make sounds when you hit them. very quickly. This movement is called a vibration. They are called percussion instruments. Drums are There must be movement to make sound. percussion instruments. Drums are played with rubber The instruments pictured make sounds. They can hammers, wooden sticks, brushes, or your hands. If make high sounds. They can make low sounds. Pitch you tap a drum lightly, you hear a soft sound. Hitting is how high or low a sound is. Objects that vibrate the drum harder makes a stronger vibration. This slowly make a low-pitched sound. Objects that vibrate makes a louder sound. quickly make sounds that have a higher pitch. You must hit or shake a tambourine to make a sound. The blocks on this instrument vibrate when they are hit with a rubber hammer. These drums are different shapes and sizes. Each one makes a sound with a different pitch when struck. 4 5 Stringed instruments are played in two ways. You can pluck the strings. Or you can rub a bow across Using Air to Make Sound The sound of your voice is made by vibrations in them. Both ways make sounds. The strings are your windpipes. When air from your lungs passes different sizes. They can be long or short and thick between your vocal cords, they vibrate. You can speak or thin. Some are stretched tighter than others. Long, and sing because your vocal cords vibrate. When you thick strings make a lower-pitched sound. Short, speak, your cords tighten. The tighter they get, the thin, tight strings make faster vibrations. They make higher the pitch of your voice. higher-pitched sounds. Your vocal cords are two pairs of thin tissue in your windpipe. Have you ever heard a harp before? The strings of this harp must be plucked to vibrate. 6 7 A wind instrument’s sound comes from vibrating air Some wind instruments use reeds. A reed is a thin inside it. Blow into a trumpet. Your lips vibrate against piece of wood. It is attached to the mouthpiece. When the mouthpiece as you blow. This makes the air inside a person blows on a reed, it vibrates. The vibration the trumpet vibrate. It also makes sound. makes the air inside the wind instrument vibrate. You can change the pitch of the trumpet’s sound The vibrating air makes a sound. If you press the keys in two ways. Change how your lips vibrate. Or of the wind instrument, you can change the pitch of press on the valves of the trumpet. Pressing on the the sound. valves changes how long the air column is inside the trumpet. All three of these wind instruments use reeds. Clarinet Saxophone Do you know how to play a trumpet? Harmonica 8 9 Sound waves travel through matter. Some of the How does sound travel? particles that make up matter get squeezed. Other What are sound waves? particles are spread apart. The particles of matter take A bell rings. Its vibrations move in the air. Some air turns being squeezed and spread out. The length of a particles are spread out. Others are squeezed together. sound wave can be measured. We measure from the The particles take turns doing this. This allows the center of one squeezed area to the center of the next. bell’s vibrations to move between these particles. This movement makes a wave called a compression wave. Sound waves are compression waves. Sound travels as waves in the air. Wavelength Sound waves from a jackhammer have lots of energy. If you were standing nearby, you would hear a very loud sound. Sound waves lose energy as they move away. Farther away, the sound would not be as loud. 10 11 Sound and Matter You hear sound only when it travels through matter. Echoes are sound waves that hit something and bounce back. Scientists use sound waves and echoes Sound can travel through solids, liquids, and gases. to study the ocean. A ship sends out a sound wave. The speed of a sound wave is different in each kind When the sound wave hits the bottom of the ocean, it of matter. bounces back. Scientists measure how long the sound The gases of air have particles that are far apart. Sound travels slowly through gases. Liquid wave takes to bounce back. Then they can figure out how deep the ocean is at that spot. particles are closer together. Sound travels more quickly through a liquid than a gas. Solid particles are closer together than gases or liquids. Sound travels fastest through solids. Sound travels at about 1,530 meters per second in water. Some whales can make sounds that can be heard up to 160 kilometers away. Speed of Sound Material Speed (meters per second) Solid—Steel 5,200 Liquid—Seawater 1,530 Gas—Air 340 Light travels faster than sound. That is why you may see fireworks before you hear them. 12 13 The Ear Many animals have vocal cords like people do. We hear sounds with our ears. The outer ear catches They make sounds when their vocal cords vibrate. sound waves. The waves travel inside the ear to the Dogs bark. Cows moo. Some animals make sounds eardrum. When the sound waves hit the eardrum, that do not use vocal cords. Bees and mosquitoes they make it vibrate. The vibrating eardrum makes make buzzing sounds when their wings vibrate. little bones vibrate. The little bones touch the shell-like Bats send out sounds people cannot hear. The inner ear. It is filled with liquid and tiny hairs. The sounds are high-pitched and bounce off insects. vibrating little bones make the tiny hairs move. The The sounds return to the bats’ ears. This helps the hairs are connected to nerves. The nerves carry signals bats find their food. to the brain. The brain recognizes the signals. Then we know what we are hearing. Many insects make sounds by rubbing body parts together. Little bones Eardrum Outer ear Chimpanzees grunt, bark, squeak, scream, and even laugh. Inner ear 14 Zebras make sounds by vibrating their vocal cords, lips, and nostrils. 15 Glossary Vocabulary What did you learn? compressionwave wave compression the wavelike movement of pitch particles squeezing together vibration and spreading out again pitch how high or low a sound is vibration the back-and-forth movement of matter Illustrations: 7, 14 Jeff Mangiat Photographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd) Opener: ©Jake Rajs/Getty Images; Title Page: ©DK Images; ©Lynn Stone/Index Stock Imagery; 2 ©Joseph Sohm/ChromoSohm Inc./Corbis; 4 (CL, BR) ©DK Images; 5 Getty Images; 6 Getty Images, 8 Getty Images; 9 (CL, CC, BL) Getty Images; 11 ©Robert Brenner/PhotoEdit; 12 ©P. Freytag/Zefa/ Masterfile Corporation; 13 ©Scott Tysick/Masterfile Corporation; 15 (CL) ©Mark Tomalty/Masterfile Corporation, (CC) ©Christiana Carvalho-Frank Lane Picture Agency/Corbis, (BR) ©DK Images, (BL) Stone/Getty Images ISBN: 0-328-13847-9 Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05 16 1. How is sound made? 2. Describe the two ways stringed instruments are played. 3. Explain how your ears help you hear. 4. In this book you have read about vocal cords and the pitch of your voice. Write to explain how their relationship works. Use details from the book. 5. Compare and Contrast How do people make sounds? How do animals make sounds? Compare and contrast the ways people and animals make sounds.