Name Lesson 1 Summary Use with pp. 391–395 Lesson 1: What causes sounds? Vocabulary vibration a very quick back-and-forth movement pitch how high or low a sound is The Causes of Sound Stringed instruments make sounds when Sounds are all around us. Some sounds they are plucked. All harp strings vibrate are soft, like falling rain. Other sounds are when they are plucked. Their vibrations loud, like car horns. Some sounds are nice make sounds. Short, thin, and tight strings to hear, like music. Other sounds might vibrate quickly. The sounds they make bother you or can even hurt your ears. We have higher pitches. Longer, thicker strings hear different sounds every day. But all vibrate more slowly. Their sounds have sounds are alike in at least one way. All lower pitches. sounds are made when matter moves. Using Air to Make Sound Sounds happen because matter moves The sound of your voice also comes back and forth very quickly, causing from vibrations. You have vocal cords in movements called vibrations. The speed your throat. The cords vibrate when air of these vibrations makes sounds different. passes between them. Your vocal cords also Pitch is how high or low a sound is. tighten when you speak. The pitch of your Objects that vibrate slowly make sounds voice depends on how tight your vocal with low pitches. Objects that vibrate cords are. The pitch of your voice is higher quickly make sounds with high pitches. when your vocal cords are tighter. Hitting or Plucking to Wind instruments make sounds when air Make Sound inside them vibrates. You make sounds on a trumpet by blowing into it and vibrating A drum makes a soft sound when you your lips. This makes an air column inside hit it lightly. A drum makes a louder sound the trumpet vibrate. You can change the when you hit it harder. The loudness of trumpet’s pitch by changing the length the sound depends on how much the of this vibrating column. You can change drumhead moves. The drumhead moves the length of the vibrating column by farther back and forth in order to make a changing how your lips vibrate. You can louder sound. also press on the trumpet’s valves. This changes the length of the vibrating air © Pearson Education, Inc. 3 column inside the trumpet. 92 Chapter 14, Lesson 1 Summary Quick Study
Name Lesson 1 Checkpoint Use with pp. 391–395 Lesson 1 Checkpoint 1. Describe some ways that sounds are alike and different. 2. How is sound made? 3. Compare and Contrast How are the sounds produced by different strings of a harp alike and different? 4. What makes the vocal cords vibrate? 5. What are two ways that sound can be different? © Pearson Education, Inc. 3 Quick Study Chapter 14, Lesson 1 Checkpoint 93
Name Lesson 2 Summary Use with pp. 396–401 Lesson 2: How does sound travel? Vocabulary compression wave a wave that has spaces where particles are squeezed together and spaces where particles are spread apart; sound waves What are Sound Waves? Particles in liquids are closer together. Think about the sound of a ringing Water is a liquid. This means that sound bell. The bell’s vibrations make sound. travels faster in water than in air. Particles Sound travels through matter. Air in solids are closer together than in liquids. particles are pushed together and spread Sound travels fastest in solids. apart. These moving particles make a The Ear compression wave. Sound waves are Our ears receive sound waves. They compression waves. The length of a sound travel on a path to the brain. The brain wave is measured from the center of one receives the signals and recognizes them compression to the center of the next as sounds. compression. The outer ear collects sound waves. The Like the bell, a jackhammer vibrates to sound waves hit the eardrum inside the make sound. These sound waves spread ear. The eardrum vibrates. This makes little out in all directions. The sound would be bones vibrate inside the ear. These bones very loud if you were standing near the are part of the middle ear. The inner ear jackhammer. But the sound waves lose has a part shaped like a shell. It is filled energy when they move away from the with liquid. The movement of the tiny jackhammer. The sound is not as loud. bones make the tiny hairs vibrate in the Sound and Matter inner ear. The hairs are connected to nerves You can hear sound only when it travels that carry signals to the brain. through matter. Sound moves through Humans cannot hear all the sounds gases, liquids, and solids. The speed of other animals can hear. Some bats make a sound wave depends on what kind of high-pitched sounds that people cannot matter it is traveling through. hear. Many animals make sounds by Air is made of gases. The particles in using their vocal cords. Many insects make gases are farther apart than in liquids and sounds by rubbing body parts together. solids. It takes longer for one gas particle Other insects make sounds by rubbing their to hit another and move the energy along. wings together. © Pearson Education, Inc. 3 94 Chapter 14, Lesson 2 Summary Quick Study
Name Lesson 2 Checkpoint Use with pp. 396–401 Lesson 2 Checkpoint 1. How does sound travel? 2. Compare and Contrast How are the sound of a jackhammer and the sound of the little bells alike and how are they different? 3. Why does sound travel quickest through solids? 4. What path do sound waves follow through the ear? 5. How do some insects make sounds? © Pearson Education, Inc. 3 Quick Study Chapter 14, Lesson 2 Checkpoint 95