How do we hear?

When something makes a noise, it sends vibrations, or sound waves, through the air.

The human eardrum is a stretched membrane, like the skin of a drum. When the sound waves hit your eardrum, it vibrates and the brain interprets these vibrations as sound.

Actually, as most things having to do with the human body, it is a little more complicated than that.

After the vibrations hit your eardrum, a chain reaction is set off. Your eardrum, which is smaller and thinner than the nail on your pinky finger, sends the vibrations to the three smallest bones in your body. First it hits the hammer, then the anvil, and finally, the stirrup. The stirrup passes those vibrations along a coiled tub in the inner ear called the cochlea.

Inside the cochlea there are thousands of hair-like nerve endings, cilia. When the Cochlea vibrates, the cilia move. Your brain is sent these messages (translated from vibrations by the cilia) through the auditory nerve.

Your brain then translates all that and tells you what you are hearing. Neurologists don't yet fully understand how we process raw sound data once it enters the cerebral cortex in the brain.

Did you know?

• Your ears aren't just good for helping you hear. They help you keep your balance as well. Near the top of the cochlea are three loops called the semi-circular canals. These canals are full of fluid that moves when you move your head. It pushes up against the cilia and sends messages to your brain that tells it how your body is moving.
• You know that feeling of dizziness after you have been spinning around? Well, the fluid in you ears spun as well. That makes the cilia move in all different directions and confused your brain.
• Children have more sensitive ears than adults. They can hear a larger variety of sounds.
• Dolphins have the best sense of hearing amongst all the animals. They are able to hear 14 times better than humans.
• Too much fluid putting pressure on your eardrums causes earaches. They are often a result of infection, allergies, or a virus.