Room Acoustics Analysis Using Circular Arrays: A Comparison Between Plane-Wave Decomposition and Modal Beamforming Approaches

A complete room acoustics analysis requires not only measurements of the single-room impulse response, but also a rigorous analysis of the sound field’s spatial properties. Angle-dependent information for the direct and reflected waves is needed for a more complete sound field description than can be obtained with single microphone measurements. Analysis techniques based on uniform circular arrays (UCAs) have attracted a lot of attention in recent years. There is also active research on beamforming methods based on circular harmonic plane-wave sound field decomposition. However, to date, there has not been a comprehensive experimental study of the acoustics of real rooms that employs both techniques. In this paper, the UCA topology is used in a comparative study for plane-wave decomposition and enhanced modal beamforming techniques. As a result, room echograms can also be obtained by calculating a set of azimuth-steered impulse responses. Experiments in real and simulated rooms are compared and discussed, with an identification of strengths and weaknesses for both measurement methods. The results show the validity of the modal beamforming approach by comparing its performance with that of the plane-wave decomposition method.