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Effect of a tilting reflective plane on the performance of an active noise control system

This article presents the results of an investigation of the noise reduction performance of a single-channel active noise control system in the presence of a tilting reflective plane. It is shown that the noise reduction achieved by the system depends upon the orientation angle of the panel and on the separation distances between both the primary and the secondary source and the reflective panel. It is also observed that the maximum noise reduction is obtained when the reflective panel is vertical and when the separation distance is less than about 0.13 of the wavelength at the frequency of interest. When the panel is moved away, the maximum noise reduction occurs at other tilting angles. Experiments were carried out in a real living room which is close to real-life situations. It is found that there is an improvement in the extent of the quiet zone in the presence of the panel. The reduction in sound pressure level is also better with the reflective panel, which is up to 20 dB.