2020 Volume 41 Issue 2 Pages 489-500
We propose a method to create a directional sound source in front of a linear loudspeaker array. The method creates clusters of focused sources to form multipoles by using a linear loudspeaker array and superposes the multipoles to synthesize a directivity pattern. We also derive an efficient multipole structure in which adjacent lower order multipoles are overlapped. The structure reduces the number of focused sources, thereby reducing the algorithmic complexity needed to create them. To further reduce complexity, we also derive a time domain implementation of the proposed method. To mitigate degradation in the reproduced directivity due to superposition of the inaccurate sound fields of focused sources, a fractional delay interpolation is applied. Computer simulation results indicate that the proposed method based on superposition of up to the third order multipoles creates a directional sound source at significantly lower complexity than a conventional method.
