The Amazing Ear
There are 206 bones in the human body. The largest bone is the femur, also known as the thigh bone, which can support up to 30 times the weight of the body. Do you know where the smallest bone is? It is in your ear. Yes, the three smallest bones in your body are part of one of the most remarkable hearing systems that has ever been designed. In this issue of Discovery, we are going to learn about the amazing human ear.
How does it work?
It is important to know that your ear is actually made up of three sections: the outer ear, the middle ear, and the inner ear. Your outer ear is the soft, cartilage part that sticks to the side of your head. It is shaped somewhat like a funnel. The main job of the outer ear is to capture sound waves. Sound waves occur when something vibrates air molecules. Your outer ear “grabs” those vibrations and sends them down the auditory (or ear) canal. The word “auditory” basically means anything that relates to hearing. This canal or tunnel is the opening where some people put a Q-tip®. It turns out that putting a Q-tip® in your ear canal can be rather dangerous if it goes too deep, and doctors warn against it. That is because the canal runs into your eardrum (also called your tympanic membrane). This thin membrane can tear or rip, which is why you don’t want to poke it with anything. When the sound waves strike the eardrum, the membrane acts like its name, a drum, and increases the intensity of the waves.
The eardrum is the structure that separates the outer ear from the middle ear. The middle ear contains the three small bones mentioned earlier. The technical names for these bones are the malleus, incus, and stapes, but they have much more fun common names. Their common names are hammer, anvil, and stirrup. You can probably guess why they have these names. One looks like a hammer, another looks like an anvil that a blacksmith would use, and the third resembles a stirrup that a cowboy would put his foot in that hangs from the saddle on his horse. These three tiny bones “collect” the sound from the eardrum and amplify it by giving it about 20 times more intensity and pressure. How do they do this? The hammer is connected to the eardrum, and the anvil and stirrup are connected to the hammer. The eardrum has a larger surface area than the stirrup bone, so when the vibrations go from the bigger area to the smaller, they get “stronger.”
Think about it like this. If you open your mouth wide and blow out air (make sure you have brushed your teeth if anyone else is around), the air does not come out very fast or powerfully. When you narrow your lips down to a small hole, you can blow with greater intensity and wind speed. Nobody blows out candles or blows up balloons with their mouth wide open. You need more air pressure to do things like that.
So, why do you need more intensity or pressure from the sound waves when they pass the eardrum? The waves go through the middle ear bones to the inner ear. The inner ear contains a structure called the cochlea. The word “cochlea” comes from the Latin word for snail. You probably didn’t know that you had a snail in your inner ear. Okay, it’s not actually a snail, but it is a bone structure that is shaped very much like a snail shell. It is filled with liquid, which is why the sound waves need to be more intense. Think about how easy it is to run through “air,” but how much more difficult it is to run when you are in water. A wave must have more force to go through water than through air. So, by the time the three tiny bones transfer the vibrations, they have amplified the waves to about 20 times their initial intensity and sent them into the cochlea.
The cochlea turns out to be one of the most complex and intriguing structures in the whole body.
After many years of serious research, our most educated doctors don’t know for sure everything that happens in this little “snail shell.” There are some things, however, that we do know. When the waves hit the bone of the cochlea, they send ripples through the liquid housed inside. These ripples cause the liquid to press down on a special membrane that “tickles” and bends the ends of tiny hairs called cilia. When the cilia bend, a small hole opens wider so that chemicals can fall into a special area beneath the cilia. These chemicals trigger an electrical impulse that runs up the auditory nerve into your brain. The brain “reads” the electrical impulse as a sound and translates it into a concept you can understand, such as music, a voice, glass breaking, etc.
The entire hearing process is one that is so well-designed, it could only have been created by a master engineer. The book of Proverbs says, “The hearing ear and the seeing eye, the Lord made both of them.” The Proverbs writer was simply showing that two of the most fascinating abilities in the world—seeing and hearing—could only have been designed by God. Who would have thought that a hammer, anvil, stirrup, and snail could take moving air molecules, and turn them into electricity that we can recognize as music!! Did you hear what I just said? No, because it is written on a page and you read it.
But, in another way, you can hear what I said. You see, the word “hear” has another important meaning. It means to understand what is being taught in a way that you respond to it correctly. Many times during Jesus’ preaching, He would conclude a sermon by saying, “He who has ears to hear, let him hear” (Matthew 11:15).
Did Jesus mean that He wanted his “hearers” to detect the sound waves in the air and think about how they were changed into electric impulses in their brains? No. He wanted them to listen closely to the meaning of His words so that they would understand the message God wanted them to know. Today, we need to hear Jesus, as well. Of course, we will not detect the moving air molecules from His actual voice, but we can read God’s Word, understand what it says, and obey Jesus, just like His original “hearers” could. Jesus once said, “Blessed are those who hear the word of God and keep it” (Luke 11:28). Do you hear what He is trying to tell you? How great it would be if everyone in the world would hear what Jesus is saying.
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