The pressure equalization between the pharyngeal area and the middle ear, which is filled with air, occurs in the Eustachian tube. Infectious mucous membrane swellings in the area where the tube discharges into the pharyngeal cavity are the most frequent reasons for problems with pressure equalization.

Air pressure decreases during ascent, resulting in an air volume increase in the air filled body cavities (middle ear, paranasal sinuses etc.). Under normal anatomic conditions the air can easily escape to the outside of the body.

As air pressure increases during descent, the air volume decreases. This produces a kind of suction in the middle ear tube area!
The air ventilation can be complicated if the suction is perturbed because of mucous membrane swellings. As a result, a vacuum-like effect develops during descent, which, in extreme cases, can cause painful bleedings or can even necessitate eardrum operations in the middle ear tube area.

Yes, with the Valsalva experiment!

Inhale deeply and hold your nose, then increase the pressure in the nasal cavity till you can notice a "crack" in the ear drum area. A soft crack is audible when the pressure has equalized.

If you already have problems with the pressure equalization in your middle ear area on ground or if equalization is rarely possible, even after several Valsalva experiments, then flying is not advisable.

Equalization delays noticed during the flight can often be treated with medications that allow the swelling to go down. It is important to take medications approx. 20 minutes before landing.

The pressure equalization with the sinuses occurs through the nose tubes. The most frequent reasons for such problems are infections with a cold or a runny nose affecting the sinuses. Painkillers and medications that allow swelling to go down can relieve the pain.