Using a spherical microphone array to analyze stage acoustics.

Abstract

A spherical microphone array, capable of beamforming, has been constructed to measure sound fields using second‐order ambisonics. The design of the microphone is based on the work by Duraiswami et al. using equations for scattering off a rigid sphere. The 16‐channel array was used to measure nine different concert‐hall stages around the state of New York, with multiple positions recorded to analyze their acoustical behavior. Additional measurements with an omnidirectional microphone were obtained to determine A.C. Gade’s stage support parameter for comparison purposes. Based on the measurements, alternative methods will be discussed to obtain better descriptors to quantify stage acoustics based on the additional spatial information the spherical microphone provides. Additionally, the work by Dammerud in developing geometric parameters based on comparisons between omnidirectional measurements and architectural dimensions will be utilized. A comparison between parameters by Dammerud and information extracted from a beamforming analysis of the ambisonic stage measurements will be shown. In particular, the comparison will examine the spatial response over time to understand how this is affected by the dimensions of the stage.