Abstract: To match the frequency characteristics of the audio or acoustic path of a hearing aid to the remainder of the hearing aid system, an acoustic path extension element (10, 25, 40, 48, 52) is interposed in the acoustic path, the extension element being structural components separable and independent of the housing of the hearing aid, although it may be retained therein (FIG. 3), to permit matching of elements having different path lengths to the hearing aid. In a preferred form, the entrance and exit openings of the separable element are coaxial to permit replacement of existing audio duct connecting tubes, at least in part, by the element and thus permit adaptation and retrofitting of hearing aids with the matching element.

Abstract: A hearing aid has a circuit board having conductor strips thereon; first plug-in elements mounted on the circuit board and being electrically connected to selective conductor strips; a plurality of circuit board-supported modular structural units; and second plug-in elements mounted on each circuit board-supported modular structural unit. The first plug-in elements cooperate with respective second plug-in elements for securing selected circuit board-supported modular structural units on the circuit board.