The use of an acoustic quiet zone as an active acoustic cloaking system

Abstract

The use of active control to acoustically cloak an object has been demonstrated previously, and is effective if the scattered component of the pressure field can be measured and directly minimised. In practice, this is non-trivial as a pressure sensor in the sound-field will detect the superposition of the incident and scattered pressures. An alternative approach is presented here which uses the control sources to generate a zone of quiet around the scattering object, with a constraint on their exterior radiation. This reduces the incident acoustic pressure on the object and thus the acoustic scattering. In this case, real-time measurements of scattered pressure or detailed geometrical knowledge of the scattering object are not required. The performance of the proposed acoustic cloaking strategy is assessed using simulated data of a rigid spherical scattering object, using a practical arrangement of control sources and error sensors. The same arrangement of sources and sensors is also used to directly minimise the scattered sound field