Abstract: An electronic coupler for a microtelephone set (14, 31) for the coupling of an amplifier (2) in a telephone line (33a) to an operating position in a telephonist-operated switchboard with automatic call distributor comprises a coupling circuit (1) with a field-effect transistor which is coupled in parallel across the amplifier (2) in such a manner that, when the supply current (E+) is coupled to the amplifier (2), it has great impedance against incoming A.C. signals in the audio frequency range, for example a ringing signal, whereby the line (29a, 29b) is connected to the telephone cartridge (14) via the amplifier (2), and also that the coupler (1) has low impedance against incoming A.C. signals when the supply current (E+) is not coupled to the amplifier (2), so that the line (29a, 29b) is coupled (37) around the amplifier (2) and connected directly to the telephone cartridge (14).

Abstract: A hook shaped part (2) for a behind the ear hearing aid. The hook shaped part is hollow and at one end (5) formed to be connected to an acoustic output from the upper front end of the hearing aid case (1) and serving to transmit sound from the hearing aid in the direction of the ear, normally through a tube (3) and an ear plug (4), and also serving to support the hearing aid upon the outer ear. In the hook shaped part there is, at the end (8) furthest from the hearing aid included an acoustic filter (9). The hook shaped part (2) has, in the direction away from the hearing aid a channel (6) of increasing cross sectional area. Through the form of the channel (6) is obtained a suppression of resonant phenomena in the tube (3) and the frequency response is made independent of the length of this tube.