Sound field separation using distributed spherical microphone array in spherical harmonics domain

In order to extract the desired target sound field from the mixed sound field, a sound field separation method using a distributed spherical microphone array is proposed. Based on the spherical harmonic decomposition of the sound field, the spherical harmonic expansion coefficients of the target sound field and the interference sound field can be obtained using the sound pressure signals received by each microphone of the array. The target sound field can be estimated from the spherical harmonic coefficients. Employing the translation of the spherical harmonic coefficients with different expansion centers, the equations between the sound pressure and the global sound field coefficients are established. The comparison is carried out with the conventional method, in which the sound field expansion coefficients with respect to the local coordinate system are calculated and transformed into the global coordinate system. The proposed method is validated through numerical simulations and experiments. The results show that, the target sound field can be accurately separated from the mixed sound field. When the energy of the interference sound field increases, the sound field estimation error of the proposed method is still small, with less increase compared to the conventional method.