[Paper] A Method of Capturing Spatial Audio in Higher Order Ambisonics Exploiting Sparsity in Plain Wave Decomposition

In this study, we investigate a method of capturing spatial sound accurately in a format of higher order ambisonics (HOA), where the sound pressure distribution is expressed with spherical harmonic series expansion, with the small number of microphones by explicitly modeling the sparsity of sound sources in space. To incorporate the sparsity, the proposed method first find a sparse solution in the domain of plain wave expansion using least absolute shrinkage and selection operator (LASSO), then convert the solution into spherical harmonic series. Computer simulation results show that the proposed method achieved improvements of approximately 30 dB in signal-to-noise ratio compared with the conventional spherical harmonic expansion based method especially when the number of microphones is small.