Implicit control applied to active shielding: Non-zero attenuation at boundaries

Active noise control is one of the more important issues in acoustics and it is related to control theory. It consists on using the superposition of waves to ensure that a controlled sound source is enough to attenuate the noise generated by one or several sources. Several applied control systems obtain high attenuation at the sensor locations. However, at other locations the attenuation cannot be ensured. Recently, the implicit control has been proposed and allows to generate arrays such that controlling the sound pressure at other locations, a desire silent zone is generated. Although it is an efficient solution when the perfect attenuation at the sensors is achieved, it has not been proven for other conditions. This paper deals with a comparison of the attenuation of the desired silent zone and the attenuation of the pressure at sensor locations. Furthermore, a statistical analysis of simulated data is carried out to determine their relation.