Sound Background Information for Teacher, Parents and Caregivers
This page provides information to support educators and families in teaching K-3 students about sound. It is designed to complement the Sound topic page on BrainPOP Jr.
Invite children to close their eyes and listen. What do they hear? How do they hear it? In this movie, they will explore sound, a kind of energy we can hear. Remind children that light and heat are other types of energy that are important to our daily lives. Sound is made when something vibrates and pushes molecules in the air to create waves. The waves travel to our ears and vibrate our eardrums, which helps us hear. Unlike light, sound waves require a medium (matter) to travel through, and they can move through solids, liquids, and gases. Sound travels faster through solids than through liquids, and more slowly still through gases. Sounds can differ in volume or pitch and they can also be absorbed or blocked by objects. An echo occurs when a sound bounces off of something and returns to its source. Remind children that sound travels slower than light, which is why they’ll usually see a flash of lightening before they hear the crack of thunder; both happen at the same time, but light reaches us before the sound does. We recommend doing plenty of hands-on activities and experiments with children to help them explore, understand, and have fun with sound.
Have children place their hands on the sides of their throats and make different sounds like humming, talking, or whispering. What do they feel? Sound is made when something vibrates, or moves back and forth. Air from the lungs pass through the vocal cords and cause them to vibrate. This helps us speak. If possible, pluck a guitar string or a rubber band to show how it vibrates. When something vibrates, it pushes particles of matter and causes them to compress. That compression then creates another next to it, and these compressions travel through matter as a wave of energy. These are sound waves. The sound waves travel through the air and to our ears and cause our eardrums to vibrate, helping us hear. Have children imagine throwing a rock in the middle of a pool or pond. Small waves move away from the rock along the surface of the water. These waves are similar to how sound waves travel through the air.
Volume describes how soft or loud a sound is. Students should know that volume, or loudness, is measured in units called decibels, with rustling leaves having a decibel level of 10, while a loud concert can have a level of 120 dB or above. If possible, use a stereo to demonstrate different volumes. The waves of loud sounds have a lot of energy and can travel far. This is why you can hear a fire truck siren or a school bell without being near it. Their sound waves can travel greater distances than softer sounds. The waves of softer sounds, such as a squeaking mouse or a whisper, do not have as much energy. You have to be pretty close to the source in order to hear them.
Pitch describes how low or high a sound is. If possible, use a stringed instrument or sing to demonstrate low notes and high notes. When you play a high note on a guitar, the string vibrates quickly and the sound waves move at a fast rate. When you play a low note, the string vibrates slower and the sound waves move at a slower rate. Remind children that just because something vibrates slower, it does not mean it’s softer. You can use a bass drum or a tuba to play low notes very loudly. The rate of vibration affects the pitch, but the amplitude, or height, of the sound wave determines the volume.
Sound waves need matter to move through, which means they cannot travel through a vacuum. Most of the sounds we hear travel through the air, but sounds can also travel through solids. Have children put their ear to a table and knock on the other side. They can hear the sound, and they will be also able to feel the vibration of the sound waves travelling through the wood. Sounds can also be blocked or absorbed by certain objects. Have children notice the difference in sound when a door or window is opened or closed. The door or window blocks out some of the sound waves and keeps them from reaching your ears. Earplugs are made to absorb some sound waves so they don’t reach your ears. People who work in loud environments, such as construction workers or ambulance drivers may use earplugs to protect their ears and hearing.
Sound waves can also bounce off things. An echo occurs when a sound bounces off something and returns to the source, or where it came from. Have children share experiences when they have heard echoes. Where were they? What did they say or hear? Some animals such as bats and dolphins use echoes to help them navigate and hunt. Bats emit a sound and use the echo to help find their way and look for food. Dolphins make a clicking noise that creates sound waves that bounce against surrounding objects; when the sound is reflected back, the dolphin can use it to visualize an image. This is known as echolocation.
Sound is all around us and helps many people and animals interact with their surroundings. Have children think about sound and how they use it everyday. Exploring sound can be a fun and hands-on way for children to learn about the world around them.
