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Method of suppression of acoustic feedback on the basis of the digital filter of preliminary calculation of a signal of correction


O.V. Nepomnyaschy, V.B. Dryzhak, K.V. Kondratyev, N.V. Matjuha, V.N.Sergeevich

At the present stage of development of means of suppression of acoustic noises, especially sharply there are problems of suppression of acoustic feedback arising at excitation of receivers of an audible tone from exterior sources of stray radiation. Known approaches to the decision of the marked problem, expressed in variety of devices of noise suppression, to some extent suppress acoustic feedback, but don't solve this problem completely. At technical implementation of such loudspeaker systems the technologies directed only on preventing of excitation are used. Within the limits of led researches by authors a row of the experimental operations with various types of similar systems has been fulfilled. Experiments show that all these devices reduce sound pressure level (that is, loudness) in sounded locations and-or distort it. In the given operation the method, allowing to lift sound pressure level in a sounded location without signal distortion and without origin of excitation owing to acoustic feedback is offered. The idea of a method consists in subtraction of a stray signal of the general, having left thus only the «useful» signal. Here the noise expresses as convolution of a signal with an impulse surge characteristic of the acoustic path which is including a radiator and the air environment. In this case implementation of the numeral filter demands the powerful calculator which is immediately behind the receiver of a signal. The main requirement to such calculator consists in that its productivity would be enough high as it is necessary to calculate convolution of a current signal with the impulse surge characteristic which length isn't less sound reverberation time indoors, for time equal to sampling interval of a signal from the receiver. As have shown results of the preliminary experiments, the offered approach can be successfully implemented by means of digital signal processors functioning in gigahertz a range
June 24, 2020
May 29, 2020

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