How hearing works

When sound waves reach your ear - for example, from a doorbell, car alarm or crying baby - you know what that sound is and you can tell if it is soft or loud.

This is because the outer ear, the visible part, collects sounds and channels those sounds down the ear canal towards the eardrum causing the eardrum to vibrate, which in turn stimulates the bones in the middle ear. These three tiny bones - known as the hammer, the anvil, and the stirrup - are the smallest bones in your body which, together, are even smaller than an orange pip. The amplified waves then travel into the inner ear, which is filled with fluid, and through the cochlea, where tiny hair cells - which can only be seen with a powerful electron microscope - pass on the vibration of the sound and turn it into electrical energy. Finally, your brain receives the energy and interprets it as, in this case, the sound of a doorbell, car alarm or crying baby.