Ear -Natomy: How we Hear
Your ears are two of the coolest parts of your body. With them you can hear all sorts of sounds, like your friends laughing or your favorite video game or cartoon. That makes your ears not just cool, but pretty important too. But how exactly do your ears work? Have you wondered how they hear all the little things that they do? It all starts with how they are made, and all of the little parts that are inside.
Your Outer Ear
There are three sections to your ears. These sections are called the outer ear, the middle ear, and the inner ear. They work together so that you can hear the world around you. When you look in the mirror, the part that you can see is your outer ear. Most of your outer ear you can touch, pull on, and you might even have them pierced if you wear earrings. There is also another part to your outer ear. This part can't be seen and is like a tube. This tube is called the ear canal. The ear canal is where ear wax is formed. The part of the outer ear that can be touched collects the sounds that you hear. The collected sounds travel down the ear canal to the second section of your ear.
Your Middle Ear
The second section of your ear is located in the middle of the ear, and it is called the middle ear. The job of the middle ear is to turn sound waves into vibrations. Your eardrum is a part of the middle ear. This is a thin piece of skin that is stretched over the end of the ear canal. It is stretched so tight that it is like a drum. Behind your eardrums are three very little bones called the ossicles. These are the tiniest bones in your body! They are named the hammer, anvil, and stirrup, and look exactly like what they are called. When sound hits the eardrum, it starts to vibrate. When the eardrum vibrates, the ossicles start to move. The ossicles carry the vibration to the inner ear.
The Inner Ear
The end of the stirrup touches the cochlea. The cochlea is another tube in the ear. This tube is curled and looks like a snail or a shell. The cochlea is filled with liquid, and it is lined with cells that are covered with tiny little hairs. But these aren't like the hair on your head at all. They are so tiny that each ear has around 17,000 of them. So, when the eardrum makes the hammer vibrate, it also causes the anvil to vibrate. The anvil causes the stirrup to vibrate. When the stirrup vibrates the cochlea also vibrates. When it vibrates, the fluid inside begins to move. When the fluid moves it bends the tiny hair cells. The outer hair cells make the vibrations stronger for the inner hair cells. The inner hair cells send a signal to the brain. When your brain gets the signal from those inner hair cells it understands that it is hearing sound. It can then figure out what your ears are hearing.
Hearing and Listening
The world is full of sounds. Some of them are sounds of things that you like and that make you happy. Other sounds you probably don't like to hear, maybe because they make you feel sad, afraid, or unhappy. Good or bad, you hear these sounds all of the time, even when you are asleep. That's because your hearing never turns off. That's why loud noises can wake you up at night. When you go to sleep at night, your ears hear what's going on around you. But because you're sleeping you're not listening! When you're awake you can control what you listen to if both of your ears are healthy. You can do this by telling your brain to concentrate on what you want to hear. Your brain tells your ears to tune down other sounds so that you can listen to the sounds that you want to hear.
Your ears are catching the sound, but your brain is really doing the hard work. Your brain sorts out the sound that comes from your ears and tells you what is being heard. If your brain doesn't hear all of the sounds, it isn't getting enough information. Without the correct information, you might not understand what you're hearing. That's why if both of ears aren't working it is hard to listen closely.
By Robert Murdock