Abstract: A hearing aid with wireless remote control of at least one of its controllable functions. The microphone of the hearing aird is used as a receiving element for the control signals. Energy (such as ultrasound) which the hearing aid microphone can transform into electrical signals which are separated from the other signals in a remote control part and caused to act upon the control members is used as a control signal transmission medium. Equipping a hearing aid with a remote control according to the invention is suited in particular for miniature hearing aids and for hearing aids insertable into the ear canal.

Abstract: An electro-acoustical transmitter converts electrical signals which correspond to acoustical events into mechanical vibrations which are transmitted onto the skin. The aim is to achieve a small vibrator which, insofar as possible, can be worn on the wrist, for instance, in the manner of a wristwatch. To that end, a coil is employed into which a magnetic core, resiliently mounted relative thereto for instance by a diaphragm, projects as an armature. The housing which carries both the diaphragm and the coil forms the magnetic return flux path. Thus, a miniaturization of the vibrator on the desired order is achieved. An inventive vibrator is particularly suited for the deaf.

Abstract: A hearing aid apparatus has a housing containing components such as a microphone, an amplifier and an earphone,and to which a terminal having contacts for connection to a signal line is applied. The terminal also has contacts for derivation of signals from the microphone so that a conventionally operating hearing aid is achieved which also contains an audio output in addition to an audio input. The hearing aid apparatus is thus particularly suitable for use as a talk/listen set in aural training systems.

Abstract: In the illustrated embodiments, a transistor amplifier stage has filter components in its input circuit providing a 12 dB/octave rise in response above a selected frequency. A bridging circuit of variable resistance may be provided for introducing a desired degree of low frequency response. A continuously controlled or switched transistor circuit may modify the resistance values in a base-emitter circuit and in a base-collector circuit of the filter network simultaneously to increase the cut-off frequency while retaining the 12 dB/octave rate of rise in response. Both the low frequency response in the attenuation range and the cut-off for the high frequency response range may be adjustable in the same amplifier stage, or a quantized selection of successive cut-off frequencies is feasible using e.g. a plurality of amplifier stages in cascade.