Weighted double sideband modulation toward high quality audible sound on parametric loudspeaker

Abstract

Recently, parametric loudspeakers have been utilized to reproduce an audible sound in a particular area by an ultrasound. However, parametric loudspeakers have lower sound quality than general electrodynamic loudspeakers because it is difficult to reproduce an audible sound at lower frequency. Moreover, the reproduced sound includes harmonic distortions causing deterioration of sound quality. Thus, in this paper, we attempt to improve sound quality of parametric loudspeakers. It depends on a modulation technique for designing the amplitude modulated wave. Therefore, we propose a new modulation method to reproduce audible sound with high quality. The proposed method controls a weight of double sidebands for reducing harmonic distortions at higher frequency and emphasizing power at lower frequency. We carried out evaluation experiments to confirm the effectiveness of the proposed method. The results confirmed that the proposed method could improve sound quality of parametric loudspeakers.

High-Presence Sharp Sound Image Based on Sound Blending Using Parametric and Dynamic Loudspeakers

“…However, the produced sound image is diffused due to the reverberation nature of the room when producing a sharp sound image such as a point-like source. In this paper, we focused on the parametric array loudspeaker (PAL) [7][8][9][10][11]. The PAL can achieve sharper directivity due to straightness of the ultrasonic wave, and it has lower reverberation than the EDL.…”

Effect of the ultrasonic emitter on the distortion performance of the parametric array loudspeaker

“…So far, there have been two hybrid modulation methods combining the DSB and SSB modulation methods. The weighted DSB modulation method makes use of the relative high audible sound pressure level of the DSB modulation method to enhance the SSB modulation method at the low frequency band [17], while the asymmetrical amplitude modulation (AAM) method is a part of the audio bandwidth extension technique for the PAL [18,19].…”