Understanding sound

Sounds are produced by vibrations - you can feel these when you put your fingers against your throat and talk. A violin bow causes a string to vibrate and lips vibrating cause the sound produced by brass instruments. By rubbing the handles of a bowl, it can be made to vibrate and when it does, the water contained within it vibrates. Polystyrene balls on the surface of a drum illustrate how a small sound is caused by a small vibration. The size of a vibration is called the amplitude. The bigger the amplitude, the louder the sound.