Study on Active Noise Control System Using Parametric Array Loudspeakers

In this paper, we propose an active noise control (ANC) system using parametric array loudspeakers (PALs). Conventional active noise control systems using ordinary loudspeakers as control sources may result in unwanted increment of sound pressure levels outside the target points (quiet zones). Moreover, a multiple-channel ANC system increases the computational complexity signi cantly as compared to a single-channel ANC system. On the other hand, the proposed ANC system can not only reduce unwanted acoustic noise levels at the desired locations but also suppress the increment in sound pressure levels at other locations because the PALs have a super-directivity feature. If interferences between di erent channels of the proposed ANC system are minimized, therefore each channel in this ANC system can be controlled independently. We have attempted to apply the proposed system in a factory where manufacturing equipments generate noise levels of over 90 dB. Due to the distribution and multiple-path propagations of noise sources, conventional ANC system cannot work e ectively. In addition, the installation locations of the control sources are constrained for safety consideration. For these reasons, comparative experiments have been conducted to nd the optimized locations to install PALs in a Case(1,2,2) ANC system. Recent results of the proposed ANC system are presented and remaining issues are discussed in this paper.