Abstract: A hearing aid has a microphone (1), or other electromechanical transducer, for converting an acoustic input signal into an electrical signal, a signal-processing and amplifying signal path (2, 3, 13, 4, 5, 6) and an output converter (7) which converts the amplified electrical signals back into acoustic signals, or in the case of an implanted hearing aid into mechanical signals, and a feedback digital finite impulse response filter (FIR filter) (9) for compensation of unwanted feedback (8) from the output converter to the microphone, in which the filter coefficients of filter (9) are determined by feeding a short pulse into the feedback signal path (5, 6, 7, 1, 2) and directly measuring the impulse response of this signal path.

Abstract: In a power sensor for RF power measurments, comprising a thin-film absorbing resistor formed on the top surface of a support member and a thermocouple which is electrically isolated from the circuit of said absorbing resistor, the absorbing resistor is formed on an insulating film of a silicon support member so as to increase the sensitivity and to facilitate manufacture thereof, the silicon support member including an island formed beneath the absorbing resistor, a thermally conducting portion formed in spaced relationship thereto with a narrow bridge portion provided inbetween, and said thermocouple being constituted by the bridge portion and by mutually spaced contact zones formed thereon.