Sound

Sound are made when something moves or vibrates. this movement creates invisible sound waves that travel through the air, water, and even walls and other objects. when these sound waves reach your ears, you hear sounds. animal and people use sound to communicate. the roar of alion can be heard more than 5 miles, or 8 kilometers, away/ when something vibrates very fast, it makes a high sound. an object that vibrates slowly makes a low sound. the violin and the double bass are musical instruments with strings. the short strings on a violun vibrate quickly and make high sounds. the long strings on a double bass vibrate slowly and make low sounds.

Sound can be loud or quite. loudness is measured in units called decibels. leaves blowing in the wind make a soft sound that is only 20 decibels. waves at the beach make a louder siund of 40 decibels. a jet airplane makes a very loud sound of 110 decibels. sound that is louder than 100 decibels can hurt you ears. many animals use their ears to pick up sound waves. once inside the ear, sound waves change into signals that travel to the brain.


Source: Encarta kids 2008/the arts/music/sound