The application relates to an in-situ method to measure and adjust the sound signal presented to the eardrum by means of a hearing aid and a hearing aid employing such a method. The filter also comprises two first exit sections which extend along the length of the entry section, which are separated by a septum, and which are provided for a first wave type. Based on the management information, a controller identifies an actual page that is configured only from tracks that do not comprise the user record, and cancels the allocation of the identified actual page to the virtual page. An external modulator intensity-modulates an optical signal using the local oscillation signal. The apparatus includes a gripper including a wire feeder for holding a plurality of insulator-sheathed electric wire elements juxtaposed on a plane, a cutter, an insulation displacement press device, with a wire-drawing device provided on the rear side thereof, and a measuring and drawing device.