Why do my ears go pop?

Andrew - I've got a friend who's in my discussion group who asked a similar question once. She loves going to the Canary Islands, and she went, she had a cold and her whole head was blocked. And when the plane took off, she found that her ears got unblocked again. And it was wonderful. So she had lovely hearing on the flight, and then when it descended her ears all blocked up again. What it seems is that there's obviously a difference in air pressure in a cabin. The air pressure is raised by taking air from the engines, bleeding it off into the cabin, but the air pressure in the cabin of an airplane is still slightly less than it is at ground level. In fact, it's about the same pressure as the top of a mountain, and that's to make sure that the stresses on the fuselage don't lead to the plane exploding. So you've got slightly lower pressure than normal, but of course, the other side of your eardrum inside your middle ear is still got the air pressure that you've got when you, when you took off. So there's an imbalance between the air pressure on one side of very drum and the other side of the eardrum. And of course, this happens when you walk up a mountain, you get similar effects going into a tunnel on a train. But your ear got a brilliant mechanism for balancing out, equalizing the pressure on both sides, and it's called the eustachian tube. The eustachian tube vents, as it were. It vents the middle ear out, back to the normal atmospheric external pressure through your nose. So, when you yawn or the experience of walking up a mountain and feeling the pressure change, or in an airplane, what's happening is the middle ear is venting itself through the eustachian tube - a little burst of air to make sure that the pressure on both sides of the eardrum is the same

Chris - And if you get a cold and it clogs up, that's why it can take a bit longer for that to happen. Thanks very much.