Issue 69 / May - June 2009
It's me, Peter, your ear!
I was impatiently waiting for my turn to tell you about myself and so about my Creator while in the previous issue, my neighbor organs in your head, the eyes, were telling you how they were placed on you as a miraculous creation and were illuminating your world. Do you wonder why I was so impatient? It is because I was in a hurry to manifest to the whole universe the One who shows such great artistry in you and has given you the ability to hear only a certain amount of the sounds created in the universe. He is the One who brings together so harmoniously all of my pieces, including the two outer spoon-shaped sound receivers of wonderful structure, which you see merely as two pieces of flesh on the sides of your head and that you do not pay much attention to. Why would I stay silent when I have been created as skillfully and delicately as the eyes?
Life without me is only silence
Every artist wishes to present his work to admiring eyes. In the whole universe, from atoms to star systems, God shows all the details of His art to you, a conscious being; and among His works, He has installed the most splendid ones in your body. He has given you reason and knowledge so that you can easily see and understand them. With knowledge, you can appreciate the meaning and different qualities of existence. However, you need another tool, your five senses, through which you will look at and learn about the material world around you and then turn this knowledge into an appreciation of the meanings behind Godâ€™s creation.
If you were not able to perceive light and color (by your eyes), your knowledge of material existence would be insufficient. Similarly, if God had not placed me in your skull, you would not be able to hear and know the songs of birds, the rustling of trees, the babbling of water, or the whistling of wind, which are each a note in the divine musical harmony throughout the universe. Indeed, everything speaks in its own tongue in order to introduce God to people. You use your eyes to perceive the things that speak with the wavelengths of light. You use me to perceive other wavelengths called â€śsound,â€ť which is caused by the vibration of molecules.
The wavelength of the sounds that I can perceive ranges between 20 and 20,000 Hertz. I am unable to sense frequencies of sound that are above or below those limits. Indeed, it would be better to call this an advantage given by God rather than an â€śinability.â€ť If the Creator of everything in the universe had not created me with this limited capacity, you would be facing unbearable pain in your head. If He had made me work with a wider range of hearing, you would be disturbed by the footsteps of a little ant, the moaning of an insect laying eggs, the buzzing of beehives, and the sound of the fluttering birds. Therefore, the fact that I have sufficient sensitivity for you to meet your needs is an advantage and an indication of Godâ€™s mercy. After all, my Creator gives everybody exactly what they need in a most suitable way and in the best measurements; He never does anything absurd. Do not ever want to have an ear like that of a bat. I am the best one for you.
Do not ever think that my outer, visible part is too simple. My outer ear, which sometimes turns red when you are nervous, is placed in the best position according to the shape of your head so that it can receive sounds in a most efficient way. Because it is made up of elastic cartilage, my outer ear (A) is very flexible, and it wonâ€™t break when you lie on it. The curves on me (known as the helix) and the hairs inside my channel are not made without a reason, either. My cartilages have the perfect shape to channel the sound down towards my middle ear according to the intensity of the sound and the direction it comes from. Because this special shape is formed according to the genetic code of a person, it is different in every person. The hairs in the canal serve to protect me from foreign objects like insects or dust. The canal that connects my outer part to my middle part is pretty wide, but if too much fatty wax accumulates here, I might experience temporary hearing loss.
My outer part is followed by my middle ear, which begins with the ear drum (tympanic membrane) (C). Attached to this thin ear drum are three bones: the malleus (D), the incus (E), and the stapes (F), which are all placed in order. These little bones are jointed to each other at an angle of 105 degrees. With an action like a piston, they amplify even the smallest sound vibration coming from the ear drum and transmit it to the middle ear. My middle ear space is connected to your pharynx by a very thin canal called the Eustachian tube (G). In order to protect my ear drum from rupture, I recommend that you open your mouth during an explosion or an intense sound. In that way, the sound waves that enter through your mouth will balance with the sound waves in my canals so that my ear drum is protected.
My inner part, followed by my middle part, is the most vital and sensitive area. Therefore, it is surrounded and protected by the bones of your skull. This inner part, which is an amazing piece of art and technology, comprises two wonderful receptor components. Those two little parts are placed in the same narrow area inside the temporal bone, but they perform different tasks. One of them is the cochlea (H), which is involved with hearing. The other part is the balance (vestibular) canals, which consist of the semicircular canals (I), the saccule (J), and the utricle (K). This balance organ enables you to stand straight and walk, run, or move without bumping or falling.
Like carved marble or forged metal, those parts are crafted out of bones that form a beautiful and intricate whole. My cochlea is divided widthwise by a bony tube. The upper compartment above the tube is connected to an oval window, which is an outlet to the middle ear. The lower compartment below the tube is connected to a round window. My inner part is a labyrinth of fluid-filled tubes. The fluid in the bony labyrinth, between the bone and the membranes, is called perilymph, and the other fluid within the membranous structure is called endolymph.
Situated on the basilar membrane (L) of my cochlea is a very small and special organ that you call the organ of Corti. The organ of Corti contains the hearing cells (or hair cells), the receptors (M) that are sensitive to sound waves, and other supporting cells. Because the length of the cells in the organ of Corti varies, different parts of my cochlea are sensitive to sounds of different wavelengths.
The sound waves travel via the malleus, the incus, and the stapes and through my oval window, agitating the perilymph of my cochlea. After that, the sound waves cause Reissnerâ€™s membrane (N) in my cochlea to vibrate, which then results in a wave movement in the endolymph. The wave movement continues along this membrane until it reaches my organ of Corti. The special receptor cells (or hair cells) of the organ of Corti are the ultimate vibration receptors. Their surfaces consist of very small strands (cilia). Those little strands bend and twist when the sound waves are received. Right at this point, a very important event occurs: it is the movement of these strands which converts the mechanical energy (that is produced by the vibrations of the sound waves) into electrical impulses. Those electrical impulses are then sent to your brain via the auditory nerve (nervus cochlearis) of the brain, where they are perceived as â€śsound.â€ť The same sound waves continue their way to the perilymph and pass into the round window, the section between the middle ear and the inner ear. The round window pushes out to dissipate the sound vibrations in the perilymph and thus lessens their pressure.
The speed of the hearing depends on the speed of the sound that travels through my membrane and little bones. However, once the sound waves begin to pass to your brain as an electrical impulse along the auditory nerve, the hearing process increases its speed. Then your brain immediately interprets and reacts to the sound waves. You are not aware of all these rapid activities which are done perfectly in fractions of a second. You only say that you can hear something ordinarily. Have you ever thought before about how hearing takes place? Do you think you would have a clue about the sounds and music in the universe if God had not created me as your hearing organ?
Think about it, Peter! God knows exactly what you need for your life and equips your body accordingly. If there were no God, would such a complicated organ as your ear form by itself in your skull? Can it be a simple â€ścoincidenceâ€ť where some biological mechanisms take place successfully and in order without any plan or project and they produce such a splendid organ as me with all my sections? Like every reasonable and thoughtful person, you now understand that I cannot be the result of simple coincidence but only a creation of our God Almighty, donâ€™t you?
Maintaining your balance
So far, what I have told you about is my duty to hear. Now I must also tell you about my duty of balance, so that you can better understand how miraculous I am.
Have you ever seen an acrobat walking on a rope or a mountain climber in action? Or shall I give a better example that might be more familiar to you? Remember what you do on your bicycle to keep from falling off. At the slightest mistake, the acrobat might topple from the rope, the climber might slip off the cliff face, and you might fall off your bicycle. While you are making unconscious (reflex) movements to keep your balance, have you ever thought about what busy operations are going on in my system? I have been equipped with very sensitive receptors which help you stay stable during your continual, different movements. Those receptors immediately recognize the changes occurring as a result of your slightest motion; they warn your body to adjust to your new position by sending out information to the spinal cord and to the brain about the new situation.
You may wonder how these two processes, hearing and balance, can take place in such a small area of the body, the inner ear. It is our Creator, God, who puts microscopic cells in a narrow place and runs the most sensitive and important operations via those little cells.
How do you feel the sensation of balance and how do you react with the right reflex action? To find an answer to that, you need to re-examine my anatomical structures mentioned before. At the base of my semicircular canals is a bulb-like enlargement which opens to the saccule and the utricle. My three semicircular canals are situated at 90-degree angles to each other in three-dimensional space.
My semicircular canals contain few sensory hair cells but there are plenty of them in the bulb-like enlargement. The strands of these cells, which are placed delicately, have enough elasticity to twist and bend during a movement. The receptors for balance in the saccule and the utricle are covered by a thin membrane which contains a gelatinous layer and tiny calcite crystals (cupula terminalis). Depending on its density, the endolymph fluid in my semicircular canals moves against the direction that your head and body move in. Similar to the uncontrolled movement of passengers in an accelerating or moving vehicle, depending on the speed and the direction, the movement and the speed of the endolymph differs from the general movement of your body. For example, when a car turns right, the passengers move to the left with the turning acceleration, and when a fast-moving car brakes suddenly, the passengers are thrown forward. Similarly, depending on its acceleration and momentum, every change in your movement causes the fluid in my semicircular canals to move. Triggered by the movement of the endolymph fluid, the gelatinous mass with the calcite pieces is displaced, causing the strands of the receptors to twist. Every movement of your head warns the cells of different parts, and via the vestibular nerve (nervus vestibularis) the nervous system is notified of changes occurring in your balance.
Thankfulness and contemplation
You have now seen what amazing works my two compartments, the balance and the hearing organs produce. All through your life, the former serves you by maintaining your balance without missing any of your movements, while the latter enables you to learn about the thousands of types of sounds in the world. Once you consider all of your movements in your life, you will see that my two organs perform their duties perfectly without ever getting tired, giving up, or complaining. We do not ask for any fee from you in return for those benefits, either. In fact, when God Almighty created you, placed us in your skull and set up our connection with the related center in your brain, He did not ask for any fee from you. All He wants you to do is to think about those blessings and be thankful to Him.
If you visited a hospital, you might see a lot of scenes which would lead you to think about Godâ€™s blessings on you and thank Him. Serious ear illnesses include middle ear infection (otitis media), which is frequently seen in children; otosclerosis, which is the limited ability of the stapes to transmit sound waves because its base becomes fixed to the oval window; and several hearing disorders which might be present at birth or occur later in life, depending on the level of damage to the auditory nerve. Witnessing the effects of those illnesses, you would understand how important it is to be able to hear and stand straight and balanced, and so see how blessed you are. At every step you take, when you are lying down or standing up, or every time you hear the twittering of birds, a nice melody, or the sweet voice of your parents, you will now appreciate the greatness and the mercy of our Lord God Almighty, who has engraved the meanings of all those sounds in your mind.
Peter! Until now, you have used me to listen to others, but today it was my turn to be listened to while I told you about myself. However, I must admit that I have only been able to explain to you the details of about one-hundredth of the beauties displayed in me and my delicate anatomical structure. If I attempted to present you with all the details about me discovered by developing technology and science and the meanings attached to them, there would not be enough pages in the magazine that you are holding now. Indeed, you do not need that much information either. My main aim here is to draw your attention to me, and thus let you know our God and bring you closer to Him. I hope I am successful in that. From now on, you will hear my ringing occasionally and remember me so that you will be saved from your heedlessness once again.
Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir, Turkey.