High altitude affects ear pressure due to changes in atmospheric pressure.
As altitude increases, the external air pressure decreases. This causes an imbalance between the air pressure in the middle ear and the external environment. The imbalance can lead to a sensation of fullness, discomfort, or even pain.
Swallowing, yawning, or chewing gum can equalize the pressure by opening the Eustachian tubes. These actions allow air to flow into or out of the middle ear. Using decongestants before flying or ascending to high altitudes can also prevent discomfort.