Abstract: A hearing aid includes a microphone (1), a signal-transmission unit (2, 3,) for forming or otherwise processing the signal, an output amplifier (4) to which an earphone (10) is connected, and a battery as the power supply. The output amplifier (4) is implemented essentially as a .SIGMA.-.DELTA. amplifier and is connected to a pulse generator (8) which produces a high-frequency pulsed clock signal in the 1 MHz region. A series-connected low-pass filter (15) is also provided. The input signal to the signal converter is a representation, produced by signal processing in the transmission unit, of the low-frequency input signal to the hearing aid, this signal being converted in the signal converter into a binary signal. The output signal (14) thus appears, after passing through the low-pass filter, essentially as an amplified copy of the low-frequency input signal.

Abstract: In a remotely controllable, especially remote-control-programmable heating aid with an external control device (1) with a keyboard (2), display device (3) and a data processing device (4) and also a hearing aid (9) controllable by the control device (1), in the control device there is a signal generator (11) actuatable and controllable via the keyboard (2) and the data processing device (4). This generator is releasably connected by a cable (12, 13, 14) to the heating aid so that the control device (1) can be used together with a heating aid to determine the hearing curve or, in general, the audiometric values of the wearer of the hearing aid in real conditions.