Active Noise Control Over 3D Space with Remote Microphone Technique in the Wave Domain

Active noise control (ANC) over space, also called spatial ANC, aims to reduce the unwanted acoustic noise over a continuous spatial region by generating an anti-noise field with secondary loudspeakers. Conventionally, a spatial ANC system is achieved by using error microphones evenly distributed over the region of interest, or evenly on the surface of a spherical region with the spherical harmonic analysis of spatial sound fields in the wave domain. A major disadvantage for these systems comes from the error microphone arrays, which have bulky cumbersome designs that block the user movement into the region. In this paper, we overcome this problem by introducing the remote microphone technique where the error signals are estimated at locations that are remote from the physical error microphones. We develop a wave domain ANC system based on the remote microphone technique for noise reduction over a spherical region. The error microphones are located away from the region of interest when the noise reduction is achieved. By simulation, we demonstrate that the proposed method can obtain comparable ANC performance to the conventional methods without remote microphone technique, while being more feasible in practice.