2.5D Localized Sound Zone Generation with a Circular Array of Fixed-Directivity Loudspeakers

This paper provides an analytical approach to generating localized sound zone close to loudspeakers in the horizontal plane using a circular array of fixed-directivity loudspeakers and an additional loudspeaker based on sound source dimension mismatch. A circular loudspeaker array and an additional loudspeaker located on the array center are simultaneously produced in mutual opposite phase. As a result, the propagated sound pressure at the reference circle for 2.5-dimensional sound field synthesis is completely cancelled, but that near the circular array is not compensated and localized sound zone generation is realized. The driving signals of the circular array of fixed-directivity loudspeakers and the produced sound pressures are analytically derived. The results of computer simulations indicate the effectiveness of the proposal. By taking the acoustic source-receiver reciprocity into account, the proposed filter coefficients of loudspeakers are also directly used for close-talking microphone array with directional microphones in the horizontal plane.