Rocket thumps a drum. "Every sound needs a drum!" he jokes.
Raven tilts her head. "Wait. What do you notice? Is there a drum inside the ear?"
Nova taps the tight drum skin. "Look at how thin and tight it is," she says. "Then look up the eardrum."
Rocket gasps. "My ear has its own drum!"
At the end of the ear canal is the eardrum.
It is a thin piece of tissue stretched tight across the canal.
When sound hits the eardrum, it vibrates, just like a drum skin.
The eardrum separates the outer ear from the middle ear.
The middle ear is a small space filled with air.
Inside are three very small bones. They have nicknames from old tools.
The hammer is joined to the eardrum. The anvil is joined to the hammer.
The stirrup is joined to the anvil. It is the smallest bone in your body!
The eardrum shakes the bones. The bones make the vibrations bigger.
Then they pass the vibrations on to the inner ear.
| Nickname | Science name | Joined to |
|---|---|---|
| Hammer | Malleus (MAH-lee-us) | The eardrum |
| Anvil | Incus (IN-kus) | The hammer |
| Stirrup | Stapes (STAY-peez) | The anvil |
A narrow tube connects the middle ear to the back of the nose.
It keeps the air pressure the same on both sides of the eardrum.
Going up or down a big hill can change the air pressure.
You may feel a little pop as your ears adjust. That is this tube at work!
| Statement | True or false? |
|---|---|
| The eardrum vibrates when sound hits it. | ? |
| The middle ear has three tiny bones. | ? |
| The hammer is the smallest bone in the body. | ? |
| A tube links the middle ear to the back of the nose. | ? |
Tiny bones, big job! Tomorrow we reach the inner ear, where vibrations become messages for the brain.