Archives of Acoustics, 31, 2, pp. 179-192, 2006

An adaptive, active noise reduction system in closed space

W. CIESIELKA
AGH University of Science and Technology Department of Mechanics and Vibroacoustics

A. GOŁAŚ
AGH University of Science and Technology Department of Mechanics and Vibroacoustics

In this article, an active noise reduction system has been described. The ANR system was made on the basis of an finite impulse response filter and realised by LMS or NLMS algorithms. Those algorithms were implemented on the dSPACE card with a floating-point processor TMS320C31. The researches were performed in an enclosure of dimensions 4.4, 3.05, 3.2m. White noise filtered by third and octave filters with mid-band frequency 125Hz were used for the experiments.
The result of experiments was a reduction of the sound pressure level, meanly from 10 to 20dB for the natural sound field. The investigations performed revealed that the location of reference and error microphones in the acoustic system - in the room, influence significantly the efficiency of the ANR system working. The investigations performed in a selected room (volume V=41.6m3 and reverberation time T=0.53s) revealed that projected and built up system gives very good effects in the active noise reduction for random, white noises of selected ranges.
Keywords: active sound control, adaptive algorithm, active noise reduction, digital equalizer
Full Text: PDF


Copyright © Polish Academy of Sciences & Institute of Fundamental Technological Research (IPPT PAN)