Sound/How we hear
Sound is made when something vibrates.
The frequency of the sound is how many vibrations pers second. It is measured in herts. Higheer pitched sounds have a higher pitched frequency.
Amplitude of a vibration is the distance between the midpoint and the furtherst point. Louder sounds have higher amplitudes. 1 kilohertz=1000 hertz.
The range of human hearing is from about 20Hz- 20,000Hz.
Sound causes air molecules to vibrate. Sound travels along the ear canal and makes the eardrum vibrate. This makes the bones in the middle ear vibrate. This sends a message to the brain along a nerve.