5 Amazing Facts About the Ear

Most people take their ears for granted, but how they enable us to hear is truly amazing. Let’s take a closer look at the fascinating complexity of our ears.

1. Turning Sound Into Hearing

Sound waves are almost everywhere. And it’s the job of the cochlea to recognize them. The cochlea is the innermost part of the ear and connects directly to the brain.

The ear picks up sound vibrations. They travel through the outer ear, then to the middle ear, and finally to the inner ear, also known as the cochlea. In the cochlea, these sound vibrations are turned into electrical signals that get sent to the brain. Then, the brain’s nerve cells take over, and we are able to perceive sound. And all of this happens almost instantaneously!

2. The Size of a Pea

Each cochlea is very small—about the size of a pea. From the outside, it looks like a tiny snail shell. Inside this tiny organ are many different structures that work together to turn sound into hearing.

The cochlea is rolled up into a spiral, but if you would unroll an average cochlea, it would be about 31.5mm long. The cochlea can be a few millimeters wide at the base, but it is only fractions of a millimeter wide towards the very top. Contained within this tiny organ is everything your body needs to begin turning sound vibrations into hearing.

3. Over 20,000 Nerve Cells

Although the cochlea is tiny, it contains over 20,000 hair cells that turn sound waves into hearing.

Each cell is less than 20 micrometers or 0.0007 inches long! The hairs vibrate back and forth in response to sound waves, and then these vibrations are turned into electrical signals that travel through the auditory nerve to the brain.

4. The Full Spectrum of Sound

These hair cells are spread along the entire length of the cochlea. If you stimulate two hair cells that are far apart, you will hear two completely different sounds. This happens because of the way that the hair cells are arranged along a membrane within the cochlea.

The membrane is short and stiff on one end and only responds to high-pitched sounds (like the chirping of a bird). The other end is longer and more flexible and only responds to low-pitched sounds (like the beating of a drum). This geography of pitches is called “tonotopy.”

5. Endolymph Makes Waves

The part of the cochlea that touches the hair cells and the membrane is filled with a special fluid called endolymph. Because this fluid is heavier than air, it moves with more force. That means the hair cells and membrane can work more efficiently in these conditions.

Learn more about how hearing—and MED-EL hearing implants—work by reading about our philosophy of providing our recipients with closest to natural hearing.