Experimental investigation of multiple-input multiple-output systems for sound-field analysis

International audienceSpherical microphone and loudspeaker arrays have been widely studied for the acquisition of spatialsound-field information. Recently, a theoretical framework, based on systems that combine both arrays, was presentedfor the spatial analysis of enclosed sound fields. Such systems are referred to as multiple-input multiple-output (MIMO)systems, and they provide means for an enhanced spatial analysis. However, their performance is limited by errors dueto spatial sampling and system model mismatch. The effects of these errors on the system performance were studiedrecently in theory, without experimental validation. Therefore, the practical usefulness of MIMO systems for roomacousticsanalysis has yet to be determined. This paper presents an initial investigation in this direction. MIMO systemperformance and limitations are first evaluated in a simulation study. The system is then studied experimentally, throughthe analysis of room impulse responses (RIRs). Experimental validation is achieved in several aspects. First, systemproperties are studied and compared to previous theoretical results. Then, MIMO processing methods are applied for aspatial analysis of early reflections in the RIR, showing that early room reflections can be identified experimentally. Theresults of this investigation suggest that MIMO systems can be employed in practice for various applications of roomacoustics