The Eustachian tube runs from the inner ear to the back of the nose and throat, and is used for mucus drainage. Sporadic opening and closing of this tube is triggered by the swallowing reflex, and helps to normalise the pressure on either side of the ear drum. When the tube fails to open, the pressure difference can be felt. This is an uncomfortable and sometimes painful experience, and is caused by changes in altitude or when a cold has affected the ears, nose and throat. There are several methods for attempting to actively relieve this pressure.
Sucking hard candy causes the swallowing reflex in the throat to become highly active, and greatly increase the chances of encouraging the tube to open. Once it does, the pressure will normalise. When suffering a cold, this method can be combined with lozenges, helping to relieve any soreness in the throat while attempting to unpop the ears.
Chewing gum has a similar affect to sucking hardy candy or a lozenge, exercising the swallowing reflex and attempting to open the Eustachian tube. The chewing motion of the jaw also can be helpful to some people, providing a subtle stretching motion to the inner ear, nose and their connecting tube.
Placing a microwaveable wheat bag against the side of the neck and over the ear can briefly alleviate the symptoms of a cold, and allow the tube to function normally. This can allow the tube to open long enough to relieve the pressure, and ease the discomfort.
Drinking water can exaggerate the swallowing reflex and activate the tube. The brief change in air pressure as the throat fills with water also can aid in opening the tube and relieving the symptoms. Taking large gulps, and trying slightly different temperatures of water -- ranging from very cold to tepid -- can also increase the chances of unpopping the ear.
Taking a hot bath, and submerging the ears just below the surface of the water, can be effective in relieving the uncomfortable pressure when suffering a cold. Combining it with other methods, such as sucking a lozenge or chewing gum, also can help to actively open the Eustachian tubes.
Consult your doctor if the symptoms persist, or before taking any medicinal remedies. Be very careful if you attempt to hold the nose and blow; this method can be effective, but also can cause damage to the inner ear.