HOW DO WE HEAR SOUND?

1 Sound waves travel through the air. Sound always travels outwards, away from the vibrating source.

2 The outer ear picks up the sound waves and sends them through the ear canal.

3 The sound waves reach the eardrum and cause it to vibrate.

4 Three tiny bones – the hammer, anvil and stirrup – in the middle ear amplify, or increase, the sound vibrations and transmit them to the cochlea.

5 The vibrations ripple through the fluid-filled cochlea causing waves.

6 Hairs lining the cochlea move and chemicals rush into the surrounding cells, creating an electrical signal which sends nerve impulses to the brain.