Localization and Categorization of Early Reflections for Estimating Acoustic Reflection Coefficients

Knowledge of room acoustic parameters such as frequency- and direction-dependent reflection coefficients, room volume or geometric characteristics is important for the modeling of acoustic environments, e.g. to improve the plausibility of immersive audio in mixed reality applications or to transfer a physical acoustic environment into a completely virtual one. This paper presents a method for detecting first order reflections in three-dimensions of spatial room impulse responses recorded with a spherical microphone array. By using geometric relations, the estimated direction of arrival (DOA) and the time difference of arrival (TDOA), the order of the respective mirror sound source is determined.

After categorization of the incident reflections with respect to the individual walls of the room, the information of DOA and TDOA of the first order mirror sound sources can be used to estimate the frequency dependent reflection coefficients of the respective walls using a modal beamformer. The results of our estimation from real measurements are evaluated and compared to the results of a simulation, while focusing on the categorization of incidence reflections.