|Our Amazing World|
How Do You Hear?
We all are probably familiar with precision instruments. These are devices that have been manufactured to a high level of exactness and high standards. Whatever function they are meant to perform they do with great accuracy. As laymen we most likely associate the term precision with manufacturing, mathematics, chemistry, the space program and such things, but not with nature. This is because most of us have been taught in school, when we were young, that the things of nature have come about by chance.1 For example, when we look at ourselves in the mirror and consider our eyes or our ears we do not think of them as being precision instruments. In fact, because my ears appear to be a little different than my brother's, and hugely different than my friend's, I might assume that they need not be precise - in comparison to a stack of laser levels in a DIY store, for example. Let's think about that stack of laser levels for a moment. When we see those laser levels sitting there in a stack we don't think to ourselves, "Now I wonder what chance process created that stack of laser levels? In fact, I wonder what law of physics made each of those laser levels in the stack?" What we actually do is look for the name of the manufacturer that made the level so that we know what quality it is. That is because we have been trained from our youth that tools we see in DIY stores are designed and manufactured by man. Intelligent beings like us. We know that each individual level in that stack has been manufactured from a plan to a particular standard and for a particular purpose. If someone were to suggest to us those levels got in that stack by chance we would call a mental institution and have them committed. We are certain that someone makes things such as tools.
Another reason we don't recognise precision in or bodies has to do with the general lack of knowledge most of us lay people have regarding its organs and their functions.2 If we took a closer look at some organ of our body, let's say our ears, would we still think they were less precise than the laser levels we see in our DIY store.
The Beginning of Sound
Before we talk about how our ear works and distinguishes sounds we need a basic understanding of the way in sound is produced. For example, when a drummer taps his drumsticks on the drum skin it begins to vibrate. This vibration is transferred to the surrounding air molecules and then from one air molecule to the next, producing what is called a pressure wave3. A pressure wave is as a repeating pattern of high and low pressure regions that are transmitted through a medium, such as air. Of course, these pressure waves would go completely unnoticed without the existence of a device called a detector. That's where our ear comes in-it is the detector.
The Pathway for Sound
As the sound wave reaches our ear it first enters through the outer ear. Here it is channelled down a passage to our middle ear, striking the tympanic membrane. (Commonly known as the Ear Drum) The tympanic membrane begins to move in and out with the variations in the pressure of the sound wave. This causes the movement of three little bones called the malleus, the incus, and the stapes, (or more commonly, the Hammer, Anvil and the Stirrup. For this is sort of what they look like.)4
What is Our Eardrum?
Our eardrum is a thin layer of living tissue that stretches tightly across the entire opening of the ear canal. As such it contains many cells that require the constant supply of blood. Therefore, throughout the eardrum there are blood vessels to carry blood to the cells. We need to remember that blood itself is made up of blood cells-so in effect the blood vessels are rivers of blood cells streaming along through the eardrum.
The Movement of the Tympanic Membrane
So just how much does our eardrum move when it is subjected to sound. When a doctor looks into your ear with an otoscope he can't see any movement because the eardrum moves by such a small amount that it cannot be observed with the human eye. In fact it takes an instrument called a Time Average Electronic Speckle Pattern Interferometer (ESPI).5 This is because the eardrum moves by one times 10-10 atmospheres. This is basically equal to a change in altitude of one thirty thousands of an inch. It is also equal to the diameter of the world's smallest element, the hydrogen atom.
The Marvel of Hearing
Our ear can distinguish sounds as varied as the beat of a drum or the whisper of a light summer breeze. It can tell the difference between an A flat and an A sharp. It can distinguish between different human voices, even if that voice is heard over a telephone or from a tapped message. This is truly amazing. But consider this. Remember we said earlier that the eardrum has blood vessels running through it, which supply blood to the cells in its tissue. That blood is made up of cells that are 6,7 microns in diameter. Now compare that to the diameter of a hydrogen atom, which is 1/1000 of a micron, or 6000 times smaller than the blood cell. (Remember that we learned the eardrum moves only by the diameter of a hydrogen atom.) As the blood cells pass through the blood vessels of the eardrum, bouncing off the walls as they go, they are setting up a certain amount of vibration. Yet this does not affect the ability of your ear and brain to distinguish all the varied sounds of life. So the next time you look in the mirror, ask yourself, "Did you really get those amazing ears by chance?" Will you take the advice of Francis Crick who said, "Biologists must constantly keep in mind that what they see was not designed, but rather evolved."7 Or will you consider the words of mathematician and philosopher William Dembski, of Baylor University, "There was a certain type of reasoning that came up over and over again whenever people tried to sift the effects of intelligence from natural causes," Dembski says. "They were looking for a combination of complexity and specification. And when those two came together, that was a reliable pointer to intelligence."8