Sound source localization of harmonic sources in entire 3D space using just 5 acoustic signals

Abstract

Sound Source Localization (SSL) has numerous applications namely machinery noise control, machinery fault localization, localization of explosives and weaponry in defense, development of hearing aids and robot’s auditory system. Beamforming and holographic SSL methods require numerous microphones and measurements for predicting source location; hence are highly expensive and time consuming. The simpler alternatives require less microphones; but are inaccurate, require high SNR, and have space of non-convergence where source cannot be uniquely localized. There is also a lack of method to localize pure harmonic sources. This paper proposes a method that addresses these limitations by accurately and quickly identifying the exact location of a harmonic sound source in the complete 3D space in acoustic free-field using just five acoustic signals. The novelties of this method are: new array design, spatially averaged Time Delay Estimation (TDE), TDE-ER (Energy Ratio) based localization, ER to remove mirror points, spectral de-noising, and solution of non-convergence. The method is rigorously tested through numerous simulations and real-life free-field experiments. A performance comparison shows that proposed method is more accurate (6.7% error) compared with the existing 3D SSL technique (11.7% error). Overall, it accurately identifies the coordinates of dominant sound source with 9.17% mean error, in presence of inherent sensor noise (14 dB SNR onwards) and background noise (8 dB SNR onwards) in complete 3D space. Interestingly, the sound source location, and sound source frequency is found to effect the consistency of TDE-based SSL methods. The presented work paves way for further advancement in 3D SSL.