3D exterior soundfield capture using pressure and gradient microphone array on 2D plane

Abstract

Two-dimensional (2D) planar array of first order microphones have been utilised in spherical harmonic decomposition based interior soundfield analysis. This paper proposes an efficient method in designing two-dimensional planar arrays of first order microphones that are capable of completely capturing three-dimensional (3D) spatial exterior soundfields. First order microphones are utilised within the array for measurements of pressure gradients, allowing the microphone array to capture soundfield components that conventional planar omni-directional microphone arrays are unable to detect. While spherical microphone arrays are capable of detecting all soundfield components, they have drawbacks in feasibility due to their 3D geometric configuration. The proposed planar array of first-order microphone provides the same functionality as a large spherical array which needs to encompass all sound sources while having a scalable geometry that lies purely in a two-dimensional horizontal plane. Simulations show the accuracy and feasibility of the proposed microphone array design in capturing a fully developed exterior soundfield.