What You Don't Know About Your Ears


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Have you ever wondered why we are able to hear sound? What it is in our ears that enables us to listen to things. I never realized how many crucial parts there are in our ears that play a huge role for us to hear!

ear-anatomy.jpg

There are three parts of the ear: the outer ear, the middle ear and the inner ear. The outer ear (the thing that sticks out of both sides of your head) is called the Pinna. It's shaped oddly because it funnels the sound waves through the ear canal. The ear canal acts as an "amplifier [to] focus the sound" to the eardrum. When the sound funnels because of the Pinna, it causes different "variations in the frequency response and the amplitude". This is how we can tell where a sound is coming from. The middle ear is made up of the Ossicles, which are three bones that are attached to the inside of the eardrum. They control the pressure changes entering from the outer ear to the inner ear. One of the bones from the Ossicles is called the Stapes. It's connected to the Oval Window, which is known as the "gateway to the inner ear". There is also a tube called the Eustachian Tube that helps to balance the air pressure as it connects the middle ear to the throat. This is why when your travelling on a plane that is either increasing or decreasing in altitude you find the need to pop your ears by swallowing to relieve that pressure. This is why the Eustachian Tube comes in handy! The inner ear has the Cochlea, a pea-size shape, that is filled with fluid that when the sound waves go through the Oval Window the fluid inside "sloshes around in waves". As the fluid swishes back and forth, the Basilar Membrane inside the Cochlea is coated with hair cells. The hair cells signals the nervous system, that sends electrochemical signals to the brain and creates what we know as sound ("Anatomy"). It's shocking how many pieces of the ear contribute to allow us to be able to hear a single sound!

            In July 1993, nineteen members of the Thames faculty of the Royal College of General Practitioners had four general practitioners measure 206 patients' ears ranging from the age 30-93 years old. They found that when a person gets older their ears get bigger by about 0.22 millimeters a year. Though they measured patients with different ethnicities and to have had a better experiment they should have separated each race and also expand the experiment to include more people of all ethnicities. This would have given an accurate measurement on each race and then they could have compared the difference between ear growths in all races ("Heathcotel"). But why is it that our ears continue to grow bigger but our bodies stop growing?

            One of the ancient beliefs in the Chinese culture is that a person's facial features tell a great deal about their personality and future. The length of the earlobe symbolizes the lifespan and the thickness of the earlobe represents wealth. So in both, the ideal ear would be to have a longer and thicker earlobe. The statue of the Buddha represents this feature as he has both long and thick earlobes ("Heathcotel").

lobes.gif

Also depending on what kind of earlobes you have, attached or free, it genetically comes from your parents. One strand from your father and one strand from your mother form to combine a chromosome pair. Then it depends which gene is more dominant and that decides whether or not you have attached earlobes like your father or free earlobes like your mother or vice versa ("Ear Genes"). So next time compare your earlobes to your parents and see which parent's gene was more dominant.

Another thing that is found in ears is earwax. Earwax develops due to the ear canal self-cleaning itself but it doesn't start to form until it becomes closer to the outside of the ear in the ear canal. The earwax helps to protect the inside of the ear from bacteria, dust, and water. Earwax contains skin cells that come from the eardrum to the outer ear by our chewing/jaw motion ("Earwax"; "Ear Wax"). So there is actually a purpose to that nasty earwax. As we learned in class from the gene discussion there are two types of earwax: wet and dry. We found that a gene actually decides which type we have. The dry gene is more common in East Asians, 80-95%, and the wet gene is 97-100% more common in those who have African and European ancestry. Scientists have found a mutation in the gene that "alters the shape of a channel that controls the flow of molecules" that is suppose to create wet earwax for East Asians but instead causes them to have dry earwax. They also believe that due to the colder climate the dry earwax could have been an adaptation ("Is"). What do you think could have been the cause for there being two different types of earwax?


Works Cited:

"Anatomy of the Ear." Music Production School. 17 Nov. 2013 <http://www.music-production-guide.com/anatomy-of-the-ear.html>.

"Ear Genes." Robert Krampf the Happy Scientist. 17 Nov. 2013 <http://thehappyscientist.com/science-experiment/ear-genes>.

"Earwax." American Academy of Otolaryngology Head and Neck Surgery. 17 Nov. 2013 <http://www.entnet.org/healthinformation/earwax.cfm>.

"Ear Wax." Medline Plus. 17 Nov. 2013 <http://www.nlm.nih.gov/medlineplus/ency/article/000979.htm>.

Heathcotel, JA. "Why Do Old Men Have Big Ears?" BMJ 1995; 311:1668 (23-30 December <http://www.medicine.mcgill.ca/epidemiology/hanley/tmp/surveys/big ears.pdf>.

"Is Your Earwax Wet or Dry?" LiveScience. 18 Nov. 2013 <http://www.livescience.com/593-earwax-wet-dry.html>.

Photo of the anatomy of the ear:

<http://www.biographixmedia.com/human/ear-anatomy.jpg>.

Photo of the different earlobes:

<http://korrektivpress.com/wp-content/uploads/2005/10/lobes.gif>.

2 Comments

This was a really interesting blog and my dad and I both have attached ear lobes which most people I've met don't have, so it was interesting reading about it. The biggest question I was wondering about is what should we do about our earwax? It sounds like we should keep some of it around but a lot of people clean there ears of it everyday. Here's a link to an article about scientists telling people to leave their earwax alone.

http://www.livescience.com/2812-hear-remove-earwax.html

I am taking a Deaf Culture class here at Penn State and we are talking about the Cochlear Implant. The C.I is a surgically Implanted device that helps deaf and hard of hearing individuals perceive sound. The device has both external and internal components that work together. In a more simplified manor, the C.I bypasses the "in put" part of the ear , meaning it is not like a hearing aid that just amplifies sound. What it does is it goes directly to the part of your ear that "connects" with the part of your brain that helps you understand sounds. Individuals must first be declared a candidate for the cochlear. There are many different levels that one has to clear to get one. For example(are they healthy enough to go through the surgery, are they at an age where they can fully acquire the ability to perceive language and learn, is their hearing loss going to benefit from the C.I technology?) Another thing people do not realize Is that with the C.I it is a life long commitment . You have to learn how to use it and keep up and learn new ways to understand language. For more information check out this website! http://www.nidcd.nih.gov/health/hearing/pages/coch.aspx

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