Patent ID: 6128392
Filing Date: 2000-10-03
Classification: H04R

Abstract:
Hearing aid having a main signal path comprised in succession of an electromechanical transducer, an A/D converter for conversion of an output signal from the electromechanical transducer into a sequence of discrete digital samples, a signal processing stage, a D/A converter for converting processed digital signals from the signal processing stage back into analog form, an amplifier and an output converter, and which is provided witha feedback signal path within the hearing aid, in which a digital filter with a finite impulse response is located, and which has a transfer function which is settable by stipulating corresponding filter coefficients, anda determination and setting circuit which determines the transfer function of the feedback signal path via which unwanted acoustic and/or mechanical feedback takes place between the output converter and the electromechanical transducer and which, depending on the determined transfer function of feedback signal path, adjusts the filter coefficient of the filter in the feedback path within the hearing aid in a manner at least partially compensating the acoustic and/or mechanical feedback;wherein the determination and setting circuit has a pulse generator for feeding short individual pulses to the feedback signal path and for measuring the transfer function of the path using an impulse response of the feedback signal path triggered by the individual pulses, the duration of the individual pulses being at most equal to 1/f, where f is the sampling frequency of the A/D converter and the D/A converter.