Directivity Control of a Large Loudspeaker by Multi-zone Control using a Small Loudspeaker Array

A directional source using a loudspeaker array has been performed based on Beamforming techniques or Kirchhoff-Helmholtz integral, and these techniques are used the same loudspeakers. However, this paper addresses the control approach for directional source implemented by two types of loudspeakers, i.e., a primary loudspeaker(large size) and control loudspeakers(small size). In this paper, the directivity control of a primary loudspeaker is implemented using a control loudspeaker array. When the primary loudspeaker emits a sound source toward two regions: audible and inaudible region, the original sound of the primary loudspeaker is generated in the audible region and simultaneously the sound is suppressed in the inaudible region by a control loudspeaker array. Therefore, the filter design approach is proposed to control the directivity of a primary loudspeaker using a control loudspeaker array based on Beamforming techniques. The feasibility study was performed using GENELEC 8240A (a primary loudspeaker) and Cambridge audio MINX min11 (control loudspeakers).