Two-dimensional exterior sound field reproduction using two rigid circular loudspeaker arrays

In exterior sound field reproduction using loudspeaker arrays, such as a single circular array, there is a trade-off between the reproduction accuracy and the filter gain of the loudspeaker array. With the aim of reproducing complex sound fields with a lower filter gain, an asymmetrical array geometry with reflections between two or more rigid arrays is introduced. This paper proposes a sound field reproduction method using two rigid circular loudspeaker arrays in a circular harmonic domain. Transfer functions that consider the multiple scattering between two rigid baffles can be represented in the circular harmonic domain. By repeatedly transforming the expansion coefficient between two coordinate systems, the circular harmonic expansion was applied to the reproduced sound field in a mixed coordinate system. Then, the driving function of the loudspeaker arrays was derived through a mode expansion. Numerical simulations were conducted to verify the accuracy of the reproduced sound field.