An adaptive, active noise reduction system in closed space

Abstract

In the demonstration an adaptive system of noise reduction is presented. Both the acoustic signals phase compensation and the adaptive digital filtering theory are employed. An incident acoustic wave is identified and a compensation signal is generated using a finite impulse response filter which coefficients are calculated in real time employing an LMS algorithm. The algorithm is implemented on a dSpace card with a signal processor (TMS320C31 Texas Instrument). In the receiving point (artificial head, real listener, receiving transducer) the disturbing signal (white noise filtered in range 50–250 Hz) is reduced by an active adaptive system. The damping coefficient that is obtained in the system varies from 10 to 20 dB. The experiment can be conducted and observed in any interior.