By Howard J. Bennett
If you have ever flown with your parents, you will remember them encouraging you to chew gum or drink a juice box when the plane was taking off and landing. The reason they did this was to lessen or prevent the earache you can get when flying. Actually, you can get an earache anytime you travel up or down in a short period of time. It’s just that plane trips cause the biggest swings away from, or back to, Mother Earth.
The question is, why do you feel this sort of pain and how does swallowing make it better?
To answer this question, we need to review the anatomy of your ear. The eardrum is positioned between two air-filled spaces: the ear canal and the middle ear. The eardrum is made from a special type of skin that resembles an audio speaker. And just like a speaker vibrates to reproduce sound, the eardrum vibrates to transmit sound into your brain.
Because air is present on both sides of the eardrum, forces in the ear canal or middle ear can affect its position. If you stifle a sneeze by holding your nose, forces push the eardrum outward. This can cause pain. If you have a cold, the eardrum may be pulled inward, which can also cause pain.
Which brings us to flying or driving up and down steep hills. You may not know this, but the atmosphere that surrounds the Earth has weight. This means there is more air pressure at ground level than at 30,000 feet above the planet.
Before you take off, the pressure in the ear canal and middle ear is the same. As the plane climbs, the air pressure in the cabin and the ear canal drops. This happens because as you go higher there is less atmosphere weighing down on your body. As a result, your eardrum is pushed outwards because the pressure in the canal is less than the pressure in the middle ear. When you land, the opposite happens. There is more pressure in the ear canal and the eardrum is pushed inward.
The easiest way to understand this concept is to do an experiment with a straw. When both ends of a straw are open, the pressure inside and outside is the same. Put the straw in your mouth and cover the far end with your finger. If you suck some of the air out of the straw, it will collapse in the middle. This happens because sucking air out of the straw makes the pressure inside less than outside.
This is where swallowing comes in. The Eustachian tube is a thin tube that connects the middle ear to the back of your throat. The Eustachian tube is a pop-off valve of sorts. When you swallow, it opens briefly letting air in or out of the middle ear to equalize the air pressure on both sides of your eardrum.
Isn’t the human body amazing?
© 2012 Howard J. Bennett. All Rights Reserved.
(First published in the Washington Post 5/8/11.)
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