During descent the passenger feels pain in the Ear, the pressure in the middle ear must be increased, the Eustachian tube (inner tube of ear) do not open readily.
The situation is aggravated if an individual has a cold or allergy or injected throat.
Pilot & passengers must consciously make an effort to shallow or yawn to stimulate the muscular action of the tubes.
Some times, it is advisable to use VALSALVA Techniques, that is to close the mouth, hold the nose & blow gently, this action forces air up to the Eustachian tubes. Children may suffer severe pain, because of ear blocks during descents. They should be repeatedly reminded to swallow or yawn.
Small babies are incapable of voluntarily adjusting the pressure in the middle ear & should be given a bottle to suck during descent.
It occurs because air must escape or be replenished through the Eustachian tube to equalize the pressure in the middle ear cavity with that of the atmosphere. If air is trapped in the eardrum, the eardrum stretches to absorb the high pressure.
The result is pain & sometimes temporary deafness, and in extreme cases it can even cause Eardrum Rupture.
Therefore it is not very prominent in climbs, but in descent, painful ear block generally occurs as result of too rapid descent.