What happens to the pressure in the middle ear as a diver ascends?

As a diver ascends, the pressure in the middle ear decreases. This is because, as a diver goes deeper underwater, the surrounding water pressure increases, which can exert pressure on the eardrum and the middle ear. When the diver begins to ascend, the external pressure reduces, meaning there is less force acting on the eardrum from outside. If the pressure in the middle ear does not equalize with the decreasing external pressure, it can lead to discomfort or even barotrauma. Therefore, it is essential for divers to regularly equalize the pressure in the middle ear during their ascent to prevent any negative effects. The awareness of this change in pressure, and the need for equalization, is a fundamental part of safe diving practices.