22 Sound

Sound written by John Lockyer

Listen. Can you hear any sounds? There are lots of kinds of sounds. Some sounds are quiet like when you whisper. dog Other sounds are loud like a dog barking or children shouting. Let's find out what sound is and how it is made.

Sound is made by moving air. When you clap your hands the air around them moves very fast and vibrates. These vibrations go into your ears. clapping A message is sent to your brain. The brain tells you the sound is your hands clapping together.

earmuffs Quiet sounds make small vibrations. Loud sounds make big vibrations. Very loud sounds can hurt your ears. People who work with noisy things need to look after their ears. hearing aid Some people don't have good hearing. They have hearing aids. A hearing aid makes sounds louder so the person can hear them.

Your ears tell you where a sound is coming from. The closer you are to a sound, the louder it is. Sound moves very fast, but it is slower than light. That's why you see lightning before you hear thunder. lightning Sound can move through air, water, metal and the ground. There are no sounds in space or on the moon because there is no air there.

Animals use sounds to help them. Dolphins and whales talk and sing together. Animals like the bear and the tiger make scary sounds to keep others away. dolphins Bats can't see well. They send out sounds. These sounds come back to them as echoes. The echoes help bats find their way around and find their food. bat