Geometry-Informed Estimation of Surface Absorption Profiles from Room Impulse Responses

This paper presents a method to jointly estimate the frequency-dependent absorption coefficients of the walls, ceiling and floor in a room from several impulse response measurements. The principle of the approach is to search among the observations for temporal windows of fixed size in which there is only one manifestation of acoustic reflection, based on the geometry of the setup which is assumed known up to some error. A probablistic procedure inspired by RANSAC that rejects putative outliers is devised for this purpose. Once the windows have been selected, the parameters of interest are estimated from the magnitude spectrograms of room impulse responses by minimizing a constrained cost function. Extensive simulation results on random shoebox rooms reveal that absorption coefficients can be efficiently recovered with the procedure, and that increasing the number of measurements improve the results while enhancing the robustness to noise and to geometrical uncertainty.