SOUND Sound is energy that travels in a wave that is caused by vibrations. Vibrations are movements made rapidly back and forth. Vibrations travel through the air and into your ear. You hear sounds when vibrating air causes your eardrum to vibrate. Strong vibrations make loud sounds while gentle vibrations make quieter sounds. Vibrations caused by sound waves cause us to hear sounds. Sound waves are the invisible movement of sound energy that travels away from the source of the sound. The farther sound waves travel, the quieter the sound becomes. Objects that make sound create high and low sounds. Pitch is the measure of how high or low a sound is. The pitch of a sound depends on how fast the vibrations are. High sounds are created by fast moving vibrations, low sounds are created by slower moving vibrations. The pitch of a sound also depends on the frequency of the vibrations. Frequency refers to the number of vibrations in a certain timeframe. Lesson Checkpoint: What does the pitch of a sound depend on? If you played an instrument with strings, you could see that the shorter the length of the string, the higher the sound it creates. The longer the length of the string, the lower the sound it creates. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Sound travels through matter. Sound waves travel through the air by spreading out in all directions. Sound waves are able to move through solids, liquids, and gases, which are the three states of matter. Sound waves travel the fastest through solids because the particles in solids are very close together. Sound waves travel slower through air than through solids or liquids because air is made of gases. The particles that make up gases are very far apart, so it takes a longer time for the sound energy to move from particle to particle in gas. Sound travels faster through warm air than it does through cooler air showing that temperature affects the speed of sound. Lesson Checkpoint: Why does sound travel fastest through solids? Turn up the volume. Volume, when referring to sound, is how loud or quiet a sound is. Sound can be measured in units called decibels. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
How We Hear We use different parts of our ears to hear sounds. Our outer ear collects the sound waves from the air. After passing through our outer ear, the sound waves reach our eardrum, which begins to vibrate. There are little bones beyond our eardrum that are located in our middle ear which also vibrate when our eardrum vibrates. Our inner ear is just beyond the little bones in our ear. There is a part of the inner ear that is filled with liquid. When the vibrations reach the inner ear, tiny hairs inside this liquid vibrate. The vibrations of the tiny hairs inside the liquid of our inner ear then send signals to our brain which then recognizes the sound we are hearing. Lesson Checkpoint: Where does sound travel after it reaches your outer ear? You make sounds when you talk because your vocal chords vibrate when air passes through them. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.