Active noise control using a virtual sensing algorithm with incident direction information of noise

Local active noise control systems create a zone of quiet around a physical error sensor location. The zone of quiet is generally small, and as such, the physical error sensor is placed at the desired location of sound attenuation, which is usually inconvenient. Virtual sensing algorithms have been developed to aim for creating the zone of quiet at virtual sensor location that is remote from the physical error sensor. However the sound attenuation of the traditional virtual sensing algorithms worsen by change of primary source location that alter the transfer characteristics between a physical sensor and a virtual sensor. This paper presents a method to maintain the sound attenuation at a virtual location in change of sound incident direction of primary source and show positive results of experiments in an anechoic room. The proposed method estimate sound incident direction of primary source to use signals of two microphones and be able to switch between an appropriate filter that is measured in preliminarily identification stage to estimate signal at virtual sensor location.