Application of beamforming techniques to the characterization of sound field variations in concert halls

The utilization of spherical microphone arrays and beamforming techniques for room impulse response measurements can deliver an important amount of information on a sound field's spatial characteristics. It permits for example a precise localization of the direct sound and the early reflections over time and space. Nevertheless, the interpretation of the results, and their relation to the subjective acoustic experience inside the room remain a challenging task. With the objective of expanding the application of 3D-beamforming to the field of room acoustics, a series of measurements has been performed in two concert halls at Konzerthaus Berlin. The corresponding results demonstrate the capability of the used microphone array to detect the acoustic characteristics variations of the room before and after the installation of an acoustic treatment behind and beside the stage. This paper presents the configuration and the analysis of the 3D-measurements and an attempt to relate the conventional room acoustics parameters with the results of the beamformer.