Design of a Highly Directional Endfire Loudspeaker Array

Abstract

The applicability of a loudspeaker line array, of which the main directivity is in the length direction of the array, is discussed. Hence this acoustic array aims at the endfire beamforming direction, resulting in a "spotlight" of sound in a preferred direction. Optimized beamforming techniques are employed, which have been developed earlier for the reciprocal problem of directional microphone arrays. Effects of the design parameters of the loudspeaker array system on its performance have been investigated. It is shown that the stability factor of the optimized beamformer can be a useful parameter to control the directional characteristics of the array. In addition the effect of mutual interaction between individual loudspeaker elements in the array system has been considered to reduce the difference between designed and actual performance of the array system. A prototype constant-beamwidth array system has been tested by simulation and measurement and the results support findings in a parametric analysis.