Directivity Synthesis with Multipoles Comprising a Cluster of Focused Sources Using a Linear Loudspeaker Array

摘要

A method to create multipoles comprising a cluster of focused sources by using a linear loudspeaker array has recently been investigated. Directivities in a listening area were confirmed with examples of primitive multipoles such as dipoles and quadrupoles. This paper describes a method to create a sound source having more complex directivity by using a superposition of multipoles comprising a collection of focused sources. An analytical method is also described with which coefficients can be obtained for each multipole by circular harmonic expansion of a sound field created by a directional sound source and Taylor expansion of the corresponding sound field. Simulation results show that a superposition of multipoles based on analytical conversion introduces desired directivities to the sound sources created in the listening area by a linear loudspeaker array.