Practical open-concentric spherical microphone array design

Abstract

The problem of higher order sound field capture is considered. First-order microphone arrays, such as tetrahedral A-format designs, are commonplace, while interest remains in the increased spatial resolution delivered by higher order arrays. Such arrays typically consist of pressure microphones mounted on a solid spherical baffle, with which higher-order spatial components are estimated algorithmically. This produces a design trade-off, with small arrays being preferred for spatial aliasing performance and large arrays being preferred for reduced amplification of microphone capsule noise at low frequencies. A practical open sphere design is proposed that contains microphones mounted at multiple radii to fulfill both criteria. Coupled with the use of cardioid microphones, such an array captures higher order soundfields over a wider audio bandwidth than baffled spherical designs of fixed radius.