HOW SOUND TRAVELS: A sound is made when something vibrates and makes particles in the air next to it vibrate. The air particles pass the vibration from one to another. You can describe a sound by showing it on a graph. The shape is called a sound wave. Different sounds have different shaped sound waves. The number of times a sound wave vibrates each second is called
frequency. A high note has a high frequency.

SOUND WAVES: The look of a sound wave varies according to what is making the sound. These sound waves are all produced by different instruments.

ELECTRONIC INSTRUMENTS: A lot of bands use electronic instruments, such as drum machines and keyboards. These sorts of instruments use a computer chip to store and reproduce sound waves.