Abstract: A device for affecting the hydrodynamic system of the internal ear, said system including the perilymph and the endolymph. A first apparatus generates a desired static-pressure level. A second apparatus varies the static-pressure level. A third connector between the first and second devices affects the static pressure level upon predetermined pressure changes in accordance with a predetermined program controlled by a control unit. The first device includes a medium pump for generating the desired static-pressure level in a medium reservoir. The second device includes a unit for causing movements of a membrane which is connected to the reservoir. These movements are arranged to cause variations of the static-pressure level. The membrane has a predetermined area, and the unit is arranged to affect the membrane by a force of a certain magnitude to generate the pressure changes.