Enhanced sound field reproduction within prioritized control region

Higher-order ambisonics has been identified as a robust technique for synthesizing a desired sound field. However, the synthesis algorithm requires a large number of secondary sources to derive the optimal results for large reproduction regions and over high operating frequencies. This paper proposes an enhanced method for synthesizing the sound field using a relatively small number of secondary sources which allows improved synthesizing accuracy for certain subregions of the interested zone. This method introduces the spherical harmonic translation into the mode matching algorithm to acquire a uniform modal-domain representation of the sound fields within different sub-regions. Then by changing the weighing of each region, the least mean squares solution can be easily controlled to cater for certain prioritized reproduction requirements. Simulations show that this technique can effectively improve the matching accuracy of a given sub-region, while only slightly increasing the global reproduction error. This method is shown to be especially effective in the situations where the number of secondary sources is limited.