A Bayesian spherical harmonics source radiation model for sound field control

Abstract

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Large-scale outdoor sound field control

“…Previous studies have mainly used simple point source models with the multi-point approach (Choi and Kim, 2002;Zhu et al, 2017) or with wave-field synthesis (Kuntz and Rabenstein, 2004;Lapini et al, 2018). Yet, it has been recently shown (Caviedes-Nozal et al, 2019b) that modeling the sound sources with higher-order spherical harmonics and estimating the corresponding mode coefficients from few in situ measurements leads to significantly better results.…”

“…The demonstration system is based on the pressurematching method to cancel the sound from a primary loudspeaker array in a dedicated control area. In the second contribution of this work, we introduce the use of a sound propagation model based on recent work by Caviedes-Nozal et al (2019b) that enables practical large-scale control outdoors as it reduces the required measurement effort considerably. We experimentally verify that such model-based sound field control with sparse measurements can have similar performance to a classic control scheme with many microphone locations in the control zone.…”

“…We propose the use of a sound propagation model that accounts for the directional properties of the sources (Caviedes-Nozal et al, 2019b) and which also accounts for a variable speed of sound to account for changes in the propagation of sound. We assume that the radiation by the loudspeakers is axi-symmetric, i.e., it is rotationally symmetric around the polar axis (the axis traversing the center of the loudspeaker driver in the normal direction).…”

“…We treat a, T, and n as stochastic variables and solve Eq. ( 5) by maximum a posteriori (MAP) estimation (Caviedes-Nozal et al, 2019b). MAP estimation can be seen as likelihood maximization with regularization priors on the unknown variables.…”

Sparse Plane Wave Approximation of Acoustic Modes to Address Basis Mismatch

“…Recently, the reconstruction of a low-frequency sound field in an enclosed space has generated interest among researchers. It is significant for many applications, including sound field auralization [1], room equalization [2], sound field control [3][4][5], etc. The reconstruction problem usually involves interpolating the impulse responses at unmeasured positions from the impulse responses measured by a discrete set of microphones.…”