Hearing

This is Ludwig van Beethoven, one of the greatest composers of all time. The music... is his own. But why does he look so sad? Maybe, because for him, it sounded like this? -- Yes.

Beethoven in fact developed a serious hearing impediment. Toward the end of his life he was not able to hear the music he created. He was deaf. This is nothing visible, of course. The ears look alright.

But hearing - and the ear - is so much more than what's attached to the outside of the head. Come along, as we follow the path of the sound through the ear to understand how it functions. The part of the ear that we can see is called the pinna. There is a reason it looks a bit like a funnel. The shape is good for focusing sound waves, say music, coming from different directions. -- The sound is channeled into and through -- the ear canal.

The pinna and ear canal together are called the outer ear. At the end of the ear canal, a membrane is hit by the sound waves, and vibrates back and forth. This membrane, the 'eardrum', is the boundary between the outer ear and -- the middle ear. Here, there are three tiny bones touching the eardrum. These are the smallest bones in the body.

Vibrating with the eardrum, they amplify the sound waves. They are called the malleus - or 'hammer' the incus - or 'anvil' and the stapes. The stapes, furthest in, transmits the sound waves deeper... into -- the inner ear. Here, a small spiral-shaped organ, filled with viscous liquid vibrates in response to the signal.

When a sound wave passes from air into a liquid, the sound is muted. You might recognise this from underwater swimming. That's why the sound waves need to be amplified before reaching the inner ear. The spiral is called the cochlea. So far, the sound travelling through the ear consists of vibrations in the air and in the organs of the ear.

But the brain cannot perceive vibration. For these signals to be sent to the brain, they must be converted into electrical signals. This conversion happens in the cochlea. Here there are hair cells that detect the vibrations in the liquid and convert them into tiny electrical signals: neural signals. These are transmitted by the hearing nerve to the brain.

And now we can perceive the sound. The brain immediately interprets the signals. We recognise voices and language sounds... ... we hear tones... ... or we might be bothered by noise...

That's how hearing works. The sound is focused and channelled through the outer ear... ... amplified in the middle ear ... and converted in the inner ear into neural signals that the brain can receive and interpret. But sometimes, like for Beethoven, there might be problems which create hearing disorders.

Loud sounds can damage the hair cells or rupture the eardrum. Because of this, hearing aids are used by many people today. There are different kinds. Some hearing devices amplify the sound for easier detection by the hearing system. Others are artificial 'cochlear implants', that can sense sound and convert it directly to neural signals that reach the brain.

This is advanced technology that has helped many people - old and young - and improved their lives. But what about Beethoven? It's believed that his hearing impediment was in the inner ear. Had he lived today, perhaps he could have had a cochlear implant. Perhaps he could have heard his own music.

And perhaps then he would have looked a bit less grumpy.