I’ve never understood to logistics of it, what happens to the eardrum during that time. Why (got me personally at least) is there more pain underwater than planes. I just don’t get it.
In: Biology
The reason there’s more pain underwater is because the pressure differential is greater there. Sea level on earth has 14.7 pounds per square inch of pressure being applied to you. That is called 1 atmosphere of pressure. Airplanes are mechanically pressurized to about what the natural pressure is at 7,000 feet, even though you’re flying at 35,000 feet altitude. The reason is that you don’t have enough air at 35,000 feet to live, so they need higher air pressure. But they don’t pressurize it to sea level pressure because it’s cheaper and easier to do it to 7,000 feet, with most people being totally fine at that level of air pressure.
The pressure at 7,000 feet is about 10 or 11 pounds per square inch of pressure, vs. 14.7 pounds per square inch at sea level. So a bit less than sea level but not a huge amount. That pressure difference is what makes your ears pop or hurt–the air in your middle ear is being compressed by the greater pressure of the water or air outside your ear, creating a relative vacuum inside your ear, which painfully stretches your eardrum inwards. Your eardrum is a fragile, delicate membrane and doesn’t like this abuse. When you ascend in a plane, the pressure inside your ear is greater than the pressure outside your ear, causing your eardrum to be pushed outwards by the higher pressure. Due to the way this body part is set up, it’s relatively easy for the air to travel from your middle ear to outside your ear, which will make the pain go away without any further action on your part. It doesn’t work well in the opposite direction, though–when the pressure is higher outside your ear than inside your ear, the air doesn’t easily travel from outside to inside your ear to equalize the pressure differential, and then you need to take action to equalize the pressure.
So when you descend in the plane, your middle ear will have lower pressure than the ambient air as the ambient air starts compressing but your middle ear has air trapped with no way to add more air to it, and a relative vacuum in the ear is created as the air pressure increases with descent. Net result is that your eardrum is pulled inwards painfully. It’s at this point that you have to “clear your ears” by chewing or drinking or swallowing, which will create a small opening, allowing air to get into your middle ear, equalizing the pressure on both sides of your eardrum.
However, water is a great deal heavier than air so a small amount of water will apply a great deal more pressure than even a large amount of air. So being at 33 feet deep in water will be one additional atmosphere of pressure, meaning that you’re getting twice as much pressure at 33 feet under the ocean than you were getting at sea level. So basically the difference in pressure between the surface of the earth and 33 feet of depth of water is the same as the difference in pressure between the surface of the earth and outer space. So the forces that make your ears hurt in an airplane also exist underwater, but the forces are much stronger underwater and your ears will hurt more.
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