Abstract: A hearing aid device for processing sound, which comprises a device for transducing sound to an electrical signal, a device for processing the electrical signal, a device for powering and regulating the processing device, and a device for transducing the processed electrical signal into sound, all these devices being enclosed in a case adapted for being inserted in an ear canal, an elastic layer defining a chamber on the outside of the case, the chamber containing a cold-curing composition consisting of at least two components, at least one partitioning wall within the chamber for separating the components from one another, the partitioning wall being adapted to be ruptured by being subjected to a pressure effect, the components being adapted, when being combined upon rupture of said wall, to provide a composition which expands during an initial curing period, and then sets rigidly with a substantial form stability.

Abstract: A hearing aid is described which comprises an outer front opening and an outer rear opening which are connectable to the respective sides of a membrane in a microphone within the housing of the hearing aid for directional use, and mechanical means for closing the outer rear opening for omnidirectional use, in which said closing means is formed and arranged so as in the closing position thereof to establish a narrow acoustically dimensioned sound passageway from the outer opening not closed to the side of the membrane corresponding to the closed outer opening. According to one embodiment, the mechanical closing means is a slide displaceable along the housing wall in which the opening to be closed is formed, and in which the narrow acoustically dimensioned passageway is an elongated recess in the displaceable slide.