Spherical Harmonic Decomposition of a Sound Field Using Microphones on a Circumferential Contour Around a Non-Spherical Baffle
Journal article, 2022

Spherical harmonic (SH) representations of sound fields are usually obtained from microphone arrays with rigid spherical baffles whereby the microphones are distributed over the entire surface of the baffle. We present a method that overcomes the requirement for the baffle to be spherical. Furthermore, the microphones can be placed along a circumferential contour around the baffle. This greatly reduces the required number of microphones for a given spatial resolution compared to conventional spherical arrays. Our method is based on the analytical solution for SH decomposition based on observations along the equator of a rigid sphere that we presented recently. It incorporates a calibration stage in which the microphone signals due to a suitable set of calibration sound fields are projected onto the SH decomposition of those same sound fields on the surface of a notional rigid sphere by means of a linear filtering operation. The filter coefficients are computed from the calibration data via a least/squares fit. We present an evaluation of the method based on the application of binaural rendering of the SH decomposition of the signals from an 18/element array that uses a human head as the baffle and that provides 8th ambisonic order. We analyse the accuracy and robustness of our method based on simulated data as well as based on measured data from a prototype.

Binaural rendering

Arrays

Scattering

Microphone arrays

microphone array

spherical harmonics

Rendering (computer graphics)

Encoding

augmented reality

Cameras

Harmonic analysis

Author

Jens Ahrens

Chalmers, Architecture and Civil Engineering, Applied Acoustics

Hannes Helmholz

Chalmers, Architecture and Civil Engineering, Applied Acoustics

David Lou Alon

Sebastià V. Amengual Garí

IEEE/ACM Transactions on Speech and Language Processing

2329-9290 (ISSN) 2329-9304 (eISSN)

Vol. 30 3110-3119

Binaural Rendering of Spherical Microphone Array Data

Oculus Inc., 2018-05-01 -- 2019-04-30.

Areas of Advance

Information and Communication Technology

Subject Categories

Fluid Mechanics and Acoustics

Signal Processing

DOI

10.1109/TASLP.2022.3209940

More information

Latest update

10/25/2023