Three-dimensional spatial analysis of concert and recital halls with a spherical microphone array

Abstract

The most well-known acoustical parameters—including reverberation time, early decay time, clarity, and lateral fraction—are measured using data obtained from omnidirectional or figure-of-eight microphones, as specified in ISO 3382. Employing a multi-channel receiver in place of these conventional receivers can yield new spatial information about the acoustical qualities of rooms, as well as the potential for new parameters that could have greater predictive power in terms of listeners' subjective preferences. In this research, a spherical microphone array was used to measure the room impulse responses of a number of different concert and recital halls. The data were analyzed using spherical harmonic beamforming techniques, along with other direction of arrival estimation algorithms, to understand how the soundfield evolves spatially over time at different points in the room. The results were compared to geometrical acoustic simulations and used to differentiate between listener positions which exhibited similar values for the standard parameters. In addition, new parameters were examined, including soundfield homogeneity and other spatial ratios.