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.

This clip is from:
Science Clips, Changing Sounds
First broadcast:
12 October 2007

Different activities can be used to demonstrate how sound is made by vibrations. Children could conduct a carousel of activities including twanging rulers against the table, blowing in bottles of water, clapping and making balloons squeak when they release air. Pupils may bring in their own instruments to identify how they make sounds and how tapping, blowing and plucking can cause vibrations.