Caution: Organs at Work - Part VI: Hearing

Everybody knows that the gauges on the dashboard are put there to tell the driver about what is going on in his car.  But how do they work?  Each device is essentially a sensory transducer (L. transducere = to lead across) with a mechanism in place that allows it to detect a physical phenomenon and convert it into useful information which, depending on the situation, the driver ignores at his peril.  One type of sensor, placed in the fuel tank, informs the fuel gauge on the dashboard about how much fuel is left, and on seeing it, the driver must decide how soon to fill up.  Another type of sensor, placed within the engine block, informs the temperature gauge on the dashboard of how hot the engine is, and on seeing it, the driver must decide whether or not the car is safe to drive.  To work properly, the car must have the right types of sensors, in the right places, providing the right gauges on the dashboard with the right information, otherwise the driver will not know the true situation and may end up running out of gas or permanently damaging his car.

This same principle (with the car) can be applied to the body and its ability to survive within the laws of nature.  Previous articles in this series have shown that the body has a whole host of sensory transducers located in exactly the right places which provide the right information to the right organs to allow it to control its metabolism and internal environment.  In general, these sensory transducers can be divided into three main types; chemoreceptors; which respond to chemicals, like the glucosensors in the alpha and beta cells of the pancreas that control the blood glucose, mechanoreceptors; which respond to motion and stretch, like the baroreceptors in the walls of the main arteries that supply blood to the brain for blood pressure control; and physical sensors; which respond to natural phenomena, like the thermoreceptors in the hypothalamus which controls the body's core temperature. 

How all of this came about by just chance and laws of nature alone, as evolutionary biologists would have us believe, goes against all common sense, human invention and reverse engineering.  After all, just like the sensors and the properly calibrated gauges on the dashboard, the systems needed to control things like blood glucose, blood pressure and core temperature are irreducibly complex in that each of them consists of different components each of which must be present and working properly to allow for life.  Moreover, just as the driver has an inherent knowledge of what the gauges on the dashboard tell him about his car's function, since the blood glucose, blood pressure and core temperature must stay within a certain range for the body to survive, this means that these systems must also have an inherent knowledge of what these parameters must be for the body to survive, something I call natural survival capacity.  Evolutionary biologists are great at imagining how all of these parts came together because they only deal with how they look but not how they must work within the laws of nature to allow for survival.

Like the rest of the body, the nervous system, which makes us aware of our surroundings, controls respiratory and cardiovascular function and lets us move about and manipulate things, needs different sensory receptors, located in the right places, to tell it what is going on inside and outside the body.  After all, if the body could not feel the ground or balance itself because it didn't know where its arms and legs are in space or whether it was upside down or not, then how could our ancient ancestors have survived? 

The nervous system has chemoreceptors that send information to the brain where it is interpreted as different tastes and smells.  Physical sensors like the photoreceptors in the retina of the eye detect light and send information to the brain where it is interpreted as vision. Mechanoreceptors in the skin send information to the brain on things like touch, pressure and vibration while others in the muscles and joints send information to the brain on limb position and muscle movement.  This article will focus on the specialized mechanoreceptors in the ear which, when stimulated by sound waves within a certain frequency range, results in nerve impulses to the brain which are interpreted as hearing

Sound Properties

Sound waves are oscillations, the back and forth movement of molecules within a medium, such as air.  These vibrations are then transmitted to adjacent molecules and spreads out in all directions.  Sound is not due to the linear movement of air for this is called wind.  Furthermore, since a vacuum has no air molecules it cannot transmit sound since there are no air molecules within it to vibrate. 

The physical nature of sound waves is that air particles alternate between being packed together in areas of high concentration, called compressions, and spread apart in areas of low concentration called rarefactions.  These compressions and rarefactions of air molecules form longitudinal pressure waves which, depending on the type of sound and the energy used to create them, have amplitude, wavelength, and frequency.  The amplitude relates to the volume or loudness of the sound and the wavelength and frequency relate to its pitch or tone.  Sound waves travel through the air at about 330 m/sec, and since light travels at 300,000 Km/sec, this means that light is literally about a million times faster than sound. 

\See: The Physics Classroom: Sound Waves and Music - Lesson 1 - The Nature of a Sound Wave

The measurement of loudness is defined by the decibel system named for Alexander Graham Bell the inventor of the telephone.  It uses as its starting point the threshold level of intensity where something can just barely be heard by the human ear.  This scale is logarithmic, meaning that a change from one absolute integer to the next represents an increase or decrease in the order of ten.  It is important to remember however that a decibel is one tenth of a bel so when comparing the intensity of one sound to another in decibels, the value must first be divided by ten. 

For example, the threshold for hearing is set at 0 decibels and normal conversation is about 50 decibels.  To figure out the difference in volume between normal speech and the threshold for hearing you first subtract 0 from 50 to get 50 decibels, then divide 50 by 10 to get 5 bels and then raise 10 to the 5th power which equals 100,000.  This means that normal speech is 100,000 times louder than the threshold for hearing.  The sound of a jet engine, at 140 decibels, is a level of intensity that can cause pain and damage to the ear.  To figure out the difference between the volume of a jet engine and normal speech subtract 50 from 140 to get 90 decibels, then divide by 10 to get 9 bels, and then raise 10 to the 9th power which equals 1,000,000,000.  A jet engine is a billion times louder than normal speech.

The measurement of frequency is defined as the number of vibrations or cycles per second (cps).  One cps = one Hertz (Hz), named for Heinrich Rudolf Hertz a German physicist who worked with electromagnetic waves and was instrumental in the later development of the radio and radar.  The higher the frequency, the closer the waves to each other, the more packed together the air molecules and the higher the pitch that is heard.  The lower the frequency, the further away the waves to each other, the less packed together the air molecules and the lower the pitch that is heard.  Normal human speech ranges from about 128 hz in males to 256 hz in females, the latter being the frequency of middle C on the piano.  The human ear can usually hear sounds between 20 - 20,000 Hz.  Oscillations of air with frequencies above this range are called ultrasound and those below it are called infrasound.  

All of these properties of sound, its different frequency and amplitude and what the human voice emits must have been taken into account by human life as it evolved to experience the sensation of hearing.  Evolutionary biologists claim that our ability to hear each other talk,came about by chance and the laws of nature alone.  I suspect that after you understand how the parts of the ear work together in an irreducibly complex fashion and have the natural survival capacity to contend with the laws of nature so that our earliest ancestors could hear well enough to talk to each other and survive, you will come to see that when Darwinists teach their acolytes about the evolution of hearing and human communication, it's the deaf listening to the deaf.    

The Parts of the Ear

The human ear is a very complex sensory organ in which all of its parts work together to produce and transmit mechanical waves of oscillating molecules to its cochlea.  Although it is in the cochlea where the nerve impulses for hearing begin, the other parts of the ear play important roles that support cochlear function.  The ear can be divided into three regions: the outer (external) ear, the middle ear, and the inner (internal) ear. 

See: Different Parts of the Human Ear: Which Ones Have You Heard Of?

The outer ear consists of the pinna (ear flap), the ear canal, and the eardrum (tympanic membrane).  The pinna acts like a satellite dish by collecting sound waves and funneling them down the ear canal to the eardrum.  The pinna is made of flexible cartilage and is important for determining the location of different sounds.  The ear canal produces wax which provides lubrication while at the same time protecting the eardrum from dust, dirt and invading microbes and insects.  The cells that line the ear canal form near the eardrum and naturally migrate outward toward the entrance of the ear canal taking with them the overlying ear wax and are shed from the ear providing a natural mechanism of wax removal.  Sound waves enter through an opening in the skull called the external auditory meatus.  They naturally move down the ear canal and strike the eardrum.  The eardrum is a very thin cone-shaped membrane which responds to sound waves by vibrating to a degree that is determined by their amplitude, wave length and frequency.  It represents the end of the outer ear and the beginning of the middle ear.

The middle ear is an enclosed air-filled chamber in which the air pressure on either side of the eardrum must be equal to allow for adequate compliance, a measure of how easily the eardrum will move when stimulated by sound waves.  The air in the middle ear tends to be absorbed by the surrounding tissue which, if not corrected, can lead to a vacuum effect and reduced eardrum compliance leading to impaired hearing.  The eustachian tube in the middle ear connects with the back of the nose and pharynx.  The muscular action of swallowing, yawning or chewing causes the eustachian tube to open, allowing ambient air to enter the middle ear, replacing what has been absorbed and equalizing the air pressure on both sides of the eardrum.  Anyone who has flown in an airplane has experienced this vacuum effect as the plane descended and felt its resolution when a popping sound in the ear signified that air had entered the middle ear through the eustachian tube.

The middle ear contains the three smallest bones in the body called the ossicles, which include the malleus (hammer), the incus (anvil), and the stapes (stirrup).  The job of the ossicles is to efficiently transmit the vibrations of the ear drum into the inner ear which houses the cochlea.  This is accomplished by the malleus being attached to the ear drum and the incus, the incus to the malleus and the stapes, and the stapes to the incus and the oval window of the cochlea. 

The cochlea is part of the inner ear and consists of three fluid-filled interrelated coiled chambers which spiral together for about two and half turns resembling a snail shell.  Within the cochlea is the organ of Corti, the sensory receptor that converts the mechanical waves into nerve impulses.  The vibrations, started by sound waves striking the eardrum and transmitted by the ossicles in the middle ear to the oval window of the cochlea, now produce fluid waves within it.  The organ of Corti contains about 20,000 hair cells (neurons) running the length of the spiraled cochlea which when stimulated by these fluid waves causes them to bend and send nerve impulses through the auditory nerve to the brain.  Higher frequencies cause more motion at one end of the organ of Corti while lower frequencies cause more motion at the other end.  The specific cochlear neurons that service specific hair cells along the organ of Corti respond to specific frequencies of sound which when sent to the auditory cortex in the brain are processed, integrated, and then interpreted as hearing.  How the brain is able to perform this feat is as yet not fully understood.

Real Numbers Have Real Consequences
Previous articles have shown that when it comes to the various parameters of life, like the blood glucose, blood pressure and core temperature (among dozens of others), real numbers have real consequences.  Not just any blood glucose, blood pressure or core temperature will do.  Each of them (along with dozens of others) must stay within a certain objective range that medical science can measure and express in a digital form.  As one example; blood glucose below
60 units or above 400 units usually results in weakness and severe fatigue and as the blood glucose drops toward 20 units, or rises up toward 1,000 units, this results in worsening organ malfunction and usually death.  When it comes to real numbers having real consequences, the same can be said for ear function and its ability to have allowed our earliest ancestors to hear well enough to communicate and to survive.   

Evolutionary biologists, using their well-developed imaginations, often expound on how all the parts of the ear must have come together by chance and the laws of nature alone.  However, as usual, they only try to explain how life looks and not how it actually works within the laws of nature to survive.  Besides the development of all of its perfectly integrated parts, they never mention the problem the ears of our earliest ancestors would have faced when it came to transmitting the vibrations of the eardrum to the organ of Corti with enough pressure to allow for adequate hearing to take place. 

Experience teaches that it is much easier to move through air than it is through water because of water’s higher density.  This means that it is much easier for sound waves in the air to move from the eardrum through the middle ear than it is for the oval window to move waves of fluid through the cochlea.  Medical science knows that without some sort of innovation this difference in air/water density would have so reduced the amplitude of the fluid waves in the cochlea that the hearing ability of our earliest ancestors would have been severely compromised and with it, their survival capacity.  

So, what feat of engineering did our ears develop to let them transmit sound waves through the outer and middle ear to the cochlear fluid with enough amplitude to allow for adequate hearing?  It is important to remember that F= PA, Force is equal to Pressure times Area.  This means that with a given force, the pressure on a given surface is inversely related to its area.  If the area decreases, the pressure on the surface increases, and if the area increases, the pressure decreases. 

It just so happens that the surface area of the eardrum is about twenty times larger than that of the oval window.  This means that the force generated by the vibrations coming from the tympanic membrane through the ossicles to the oval window naturally increases twenty fold on the cochlear fluid.  It was this mechanical advantage of their larger eardrums transmitting vibrations through their ossicles to their smaller oval windows of their cochleae that allowed our earliest ancestors ears to have adequate hearing so they could survive within the world of sound. 

When evolutionary biologists talk about hearing, not only do they leave out how it is irreducibly complex (all of the parts of the ear and the brain are needed for proper function) but also that it demonstrates natural survival capacity, in that the surface area of the eardrum and the oval window perfectly matched up so that our earliest ancestors could hear well enough.  Remember, when it comes to life and the laws of nature, real numbers have real consequences.  Without this set up between the eardrum and the oval window our earliest ancestors would have been as deaf as adders.  But of course, as most people who believe NeoDarwinism mistakenly teach, evolution would then have just made them develop infrared sensitivity instead (like adders) because that would have been what they needed to survive.   

 

Be sure to catch all of the articles in Dr. Glicksman's series, "Beyond Irreducible Complexity."



Howard Glicksman M. D. graduated from the University of Toronto in 1978. He practiced primary care medicine for almost 25 yrs in Oakville, Ontario and Spring Hill, Florida. He now practices palliative medicine for a Hospice organization in his community. He has a special interest in how the ethos of our culture has been influenced by modern science’s understanding and promotion of what it means to be a human being.

Comments and questions about this article or any of the previous ones are welcome.

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Copyright 2016 Dr. Howard Glicksman. All rights reserved. International copyright secured.

November 2016