Controlling double dipole loudspeaker radiation by adapted input filtering

Most flat panel loudspeakers grant good structural integration properties due to the lack of an enclosure. However the backward radiation of a dipole is not desired in many applications. In this paper, a system which achieves a high suppression of the backward radiation using a pair of dipole speakers with adapted input signal filters, is proposed. Furthermore the system does not produce any audible changes to the acoustic signal of the forward direction. Hence the sound is perceived as radiated by a single loudspeaker. Additionally, the expansion to stereo radiation with highly suppressed acoustic crosstalk of both directions is presented. The filter design as well as a calibration algorithm for any given pair of dipole loudspeakers is explained. The good performance of the developed system is proven by measurement results with a prototype system.