Active noise control with a virtual acoustic sensor in a pure-tone diffuse sound field

Abstract

Local active noise control systems can be used to generate a zone of quiet at a physical error sensor using one or more secondary sources to cancel the acoustic pressure and its spatial derivatives at the sensor location. The resulting zone of quiet is generally limited in size and as such, placement of the physical error sensor at the location of desired attenuation is required, which is often inconvenient. Virtual acoustic sensors overcome this by projecting the zone of quiet away from the physical error sensor to a remote location. The work described here investigates the effectiveness of using virtual microphones and virtual acoustic energy density sensors in a diffuse sound field. Expressions for the performance of the virtual microphones and virtual acoustic energy density sensors have been developed using the forward-difference extrapolation technique which has been rederived for use in diffuse sound fields. Results from simulations will be presented, together with experimental results obtained in a reverberant chamber.