This investigation is concerned with generating a controlled sound field for listeners inside a circular array of loudspeakers without disturbing people outside the array. Ideally this configuration would have the advantage that reflections from the surroundings would be of no concern. Inspired by the Kirchhoff-Helmholtz integral theorem a double-layer array of loudspeakers is used. Several solution methods are suggested and examined with computer simulations: pure contrast control, pure pressure matching, and a weighted combination. In order to compare the performance of the methods two performance indices are used, i) the ratio of the sound energy in the listening zone to the sound energy in the quiet zone, and ii) a normalised measure of the deviations between the desired and the generated sound field in the listening zone. The best compromise is obtained with the method that combines pure contrast control with a pressure matching technique.
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