A design of reflective audio spot with parabolic reflector for sound pressure improvement on separating emission of carrier and sideband waves

摘要

A parametric loudspeaker can represent the audible sound to a narrow spatial area because of its sharper directivity. However, even in the parametric loudspeaker, acoustic reflections and intercepts become noise. To solve this problem, we have already proposed the audio spot design method based on separating emission of the carrier and sideband waves using multiple parametric loudspeakers. However, the former method has had the problem that the audio spot has a low sound energy. In this paper, we therefore propose a new audio spot design method based on separating emission of the carrier and sideband waves using the parabolic reflectors to achieve a large sound energy on the audio spot. The proposed method achieves the audio spot design with the large sound energy by re-collecting the carrier and sideband waves passed through the audio spot using the parabolic reflectors. It is important for the proposed method to utilize the parabolic reflectors corresponding to the carrier and sideband waves. Thus, we investigate the suitable curvature of the parabolic reflectors. We carried out the evaluation experiment for measuring the spatial distribution of the demodulated audible sound energy. As a result of the evaluation experiment, we confirmed the effectiveness of the proposed method.