It is caused by the decrease in atmospheric air pressure around you as the plane ascends. The pressure change causes the air within your eardrum to expand.
The air high above the Earth’s surface is much thinner than the air closer to the surface. This is because the air near the surface has all the air above it compressing, making it thicker. Your inner ear is naturally full of air, and the change in air pressure causes pressure on your eardrum. As you ascend in an airplane and the air pressure decreases around you, the air trapped in your ear causes your eardrums to expand. This causes the discomfort of your ear “popping”, and also a decrease in hearing ability, because the pressure makes it more difficult for sound to enter your eardrums.
Your body can equalize the pressure between your inner ear and the atmosphere by releasing air from your inner ear through the Eustachian tubes. These are two small channels that connect the inner ear to the throat. When opening these tubes, you can feel the pressure release and your hearing will become clear, causing the “pop”. If you are congested, the Eustachian tubes may be blocked, which could prevent your ears from popping.
The next part is from personal experiences. These are some great ways to relieve the pressure on your eardrums:
- Chew gum
- Drink something
- Pinch your nostrils shut, suck in air through your mouth, then force the air through your nose as if you were blowing your nose.
- This mainly is used on babies and small children, but can work on anyone: gently rub your neck from the chin to the base of the neck. This will cause a swallowing reflex that will alleviate the pressure built up in your ears.