Contrary to the active detection methods, the passive sound source localization technologies only rely on the differences between the arrival time of the signals recorded by different receivers to locate the object transmitting the sound wave, without the knowledge of the sound source profile and excitation time. It has a wide application in robot hearing, UAVs (Unmanned Aerial Vehicles) tracking, and smart home devices. However, the detection capability of the sound source localization method is greatly limited by the source strength: when the source strength is too weak or the distance from the source to the receiving array is too far, the sound intensity recorded by the receiver will be very weak and greatly overwhelmed by the random noise of the receiver.This paper proposes to develop a parabolic reflector system to enhance the sound intensity recorded at the receiver, thus increasing the detection range. In order to validate this idea, a circular array of receivers is applied to record the sound signals. Instead of dealing with the data in the time domain using the information of time arrival, the FDCC (Frequency Domain Cross Coherence method) is applied for data processing. Due to the variance of the sound source and background noise in the frequency spectrum, the SNR (signal to noise ratio) is greatly enhanced. The location of the sound source is recovered through the Norm-1 regularized ADMM (Alternating Direction Method of Multipliers method) in both 2D and 3D. In the experiment results, it is found that the DOA (Direction of Arrival) can be accurately recovered in the image. Moreover, when the sound source is in the normal direction of the circular receiver plane, the distance of the sound source also could be detected by increasing the sparsity level of the reconstruction. Considering the fact that the data is recorded in a real-time fashion, this method could be regarded as a real-time method to monitor the sound source.Moreover, the feasibility of applying parabolic reflectors to this system has been investigated. Due to the large impedance mismatch between the air and plastic, a custom-designed reflector could be fabricated through 3D printing. By putting the receiver array at the focal point of the parabolic reflector, the received signal could be greatly enhanced as indicated by the simulation results. Meanwhile, re-directed by the reflector, the incoming sound wave cannot be regarded as propagating in the free space anymore, which increases the difficulties in the sound source localization. However, with the knowledge of the profile of the reflector, the proposed FDCC combined with the ADMM method still successfully recovers the location of the sound source, which paves the way for the real-time sound source localization using compressive reflectors.

Real-Time Sound Source Localization Using a Parabolic Reflector

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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