Using a planar array of microphones and loudspeakers, the authors show in this work a theoretical approach to actively suppressing the reflection of sound from boundaries, such as room walls. The filters that are proposed are applicable to real-time implementations and it is shown that the active absorption is similar to that of passive fibre panel absorption.
J. Donley, C. Ritz, and W. B. Kleijn, “On the Comparison of Two Room Compensation / Dereverberation Methods Employing Active Acoustic Boundary Absorption,” in 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2018, pp. 1-5.
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In this paper, we compare the performance of two active dereverberation techniques using a planar array of microphones and loudspeakers. The two techniques are based on a solution to the Kirchhoff-Helmholtz Integral Equation (KHIE). We adapt a Wave Field Synthesis (WFS) based method to the application of real-time 3D dereverberation by using a low-latency pre-filter design. The use of First-Order Differential (FOD) models is also proposed as an alternative method to the use of monopoles with WFS and which does not assume knowledge of the room geometry or primary sources. The two methods are compared by observing the suppression of reflections off a single active wall over the volume of a room in the time and (temporal) frequency domain. The FOD method provides better suppression of reflections than the WFS based method but at the expense of using higher order models. The equivalent absorption coefficients are comparable to passive fibre panel absorbers.