Design of a compact array with pseudo point sources using the open-ended flexible tubes

Abstract

This work proposed a method to achieve a compact source array constituted by the open-ended, flexible tubes connected to the loudspeakers as elementary sources. For the removal of the effects of pipe resonances caused by a finite length and the distortion of the transferred sound due to the area difference between tube and loudspeaker, a tube-connected source is modelled analytically by employing the measured source parameters. The calculated transfer matrix based on the model is used to obtain the inverse filter between the source plane and tube aperture. The tube resonances below 5 kHz are well suppressed except for the increasing discrepancies at high frequencies. The directivity index remains below 0.5 dB for the frequency range lower than 5 kHz on the aperture plane of the tube, indicating the achievement of a pseudo point source. The controlled test with a tetrahedral array reveals the capability of sound beam steering in the desired direction by employing the tube-connected pseudo point sources.