You may have noticed that your ears sometimes 'pop' when flying in an airplane. This may also occur while driving in the mountains or riding in an elevator. The reason for this, is that your middle ear requires air inside it to function. When the pressure inside the ear is different from the outside pressure, which decreases at higher altitudes, it builds up. The eustachian (YOU-STAY-SHE-EN) tube connects the ear to the back of the throat and allows the air pressure to equalize. Children, especially infants, have small eustachian tubes, which makes the process more difficult. Adults with colds or nasal congestion may also have problems with pressure build-up. Normally, swallowing or chewing gum will relieve the sensation. An oral or nasal decongestant taken prior to the flight may also help. If symptoms continue after your flight, consult an ear, nose and throat doctor to see if there might be complications that require more specialized treatment.