Near-Field Sound Control Using a Planar Loudspeaker

Abstract

Recent high-resolution video technologies have enhanced the immersive experience of reproduced video content. To generate auditory images that can integrate with such high-resolution video, many spatial sound-rendering methods have been proposed. However, with such advanced methods, creating a convincing near-field sound image remains a challenge. In order to render such a near-field sound image in a relatively simple yet effective way, the authors have proposed a new method using an overhead planar loudspeaker. The subjective evaluation results showed that planar waves radiating from an overhead position generated a sound image very near to the listener when coupled with an additional filter that removes spectral cues associated with an overhead sound source. The results also showed that the proposed method could continuously control the distance of sound image between a screen and a listener position. Additional physical measurements revealed that the planar loudspeaker generated a smaller variance of group delay function at the listener's ears than conventional loudspeakers. This smaller variance of group delay function was the physical parameter associated with the near-field images.