Selective distance recording using acoustic lenses

Abstract

The purpose of this study is to emphasize sound from a specific place by using an acoustic lens in sound recording. Signal processing related to sound source separation using a microphone array has been studied as a robust sound recording technique against ambient noise; however, real-time processing is still difficult to implement because of its calculation cost. On the other hand, a directional microphone can realize high sensitivity in a specific direction; but, it is unable to show such selectivity for the distance. This paper has proposed a method of removing the arrival time difference of sound waves from a specific position by utilizing an acoustic lens composed of multiple horns. The distance selectivity and speech intelligibility were evaluated for a prototype acoustic lens made by a 3D printer. As a result, it was confirmed that sound recorded with the acoustic lens had a higher sound pressure level than that recorded with a conventional microphone for a desired position, and high speech intelligibility was constantly maintained up to the desired sound source distance.