Sound comes from vibrations — Physics, 4–6 years
Sounds begin when something moves quickly back and forth. The movement travels through the air to our ears, where we hear a sound.
Tiny back-and-forth movements
A vibrating object moves back and forth very quickly. It makes nearby air move too, and that moving air reaches your ears as sound. A drum skin, a guitar string, and your voice box can all vibrate and make sounds.
Why sound needs movement
People wanted to know how a voice, a bird, or a drum could be heard from a distance. The useful clue was movement: something shakes, the air carries that shaking, and ears notice it. If nothing vibrates, there is no sound to hear.
See a rubber-band vibrate
Stretch a rubber band around an empty box. Pluck the band once and watch it blur as it moves back and forth. You hear a twang at the same time. Touch the band gently to stop its movement; the sound stops too.
Sound is not only air
You may think sound is something that floats through the air like a smell, because that is how we usually hear it. But sound starts with a vibrating object. Air carries it to your ears; placing your ear on a table can also let you hear vibrations through the table.
Talking, music, and alarms
Your voice uses vibrating parts in your throat, and instruments use vibrating strings, skins, or air. A phone speaker vibrates to make speech and music, while a buzzer vibrates to warn us. Sound helps people communicate, enjoy music, and notice danger.
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