Object Surface Recognition using Microphone Array by Acoustic Standing Wave

This paper proposes a microphone array with a speaker to recognize the shape of the surface of the target object by using the standing wave between the transmitted and the reflected acoustic signals. Because the profile of the distance spectrum encodes both the distance to the target and the distance to the edges of the target's surface, this paper proposes to fuse distance spectra using a microphone array to estimate the three-dimensional structure of the target surface. The proposed approach was verified through numerical simulations and outdoor field experiments. Results showed the effectiveness of the method as it could extract the shape of the board located 2m in front of the microphone array by using a chirp tone with 20kHz bandwidth.