Analytical approach to 2.5D sound field control using a circular double-layer array of fixed-directivity loudspeakers

This paper provides a regularization-free analytical approach to 2.5D interior and exterior sound field control using a circular double-layer array of fixed-directivity loudspeakers not only to provide a desired sound field inside the array but also to reduce the sound energy outside of it in the horizontal plane. The proposed method analytically derives the driving functions of the inner and outer circular arrays based on 2.5D spherical harmonic expansion to simultaneously control both sound fields inside and outside the array by a mode-matching framework. The results of computer simulations show that the proposed method is certainly effective compared with the conventional least squares approach that requires regularization schemes in terms of synthesis accuracy inside the listening zone over a wideband frequency range and the acoustic contrast between the quiet zone and the synthesis center at low frequencies.