Research On Indoor Acoustic Localization Using Direct Path Dominance Test Method And Spherical Harmonic Domain Theory

Sound source localization/direction of arrival(DOA)using microphone arrays is quite a significant research area in the process of acoustic signal processing.In recent years,spherical microphone arrays have been widely used in acoustic research fields such as sound source localization because the sound fields can be recorded and analyzed rapidly in a spatial region.The higher-order speech signals received by the spherical microphone array can be converted to the spherical harmonic domain for processing,using a set of orthogonal spatial functions to decouple the frequency and angular components,making it easier to achieve three-dimensional spatial sound source localization.Compared with single-source localization,multi-source localization remains more challenging and untouched to achieve precise localization due to the overlapping of multiple speakers’ voices and reverberant reflection effects.However,most of the existing spherical harmonic domain sound source localization methods are difficult to achieve the accuracy requirements of actual indoor reverberant noise environment localization.Therefore,to improve the detection performance and localization accuracy of localization methods,this manuscript focuses on the study of multi-source localization methods using spherical microphone arrays in indoor reverberant scenarios.The main work and contributions of this manuscripts are as follows:1,Firstly,the performance of existing spherical harmonic domain multi-source localization methods in low and medium-reverberant environments is analyzed by experimental simulations.These methods consist of plane-wave decomposition-steering response power,pseudo-intensity vector,subspace pseudo-intensity vector,MUSIC,MUSIC-group delay,minimum variance distortionless response,and maximum likelihood estimation method.Among these methods,the plane wave decomposition-steering response power and maximum likelihood estimation are both having low resolution and cannot be distinguished by two sources with 50° resolution,which are suitable for single-source localization.Since the noise subspace obtained by matrix eigendecomposition is used to estimate the sound source direction,the localization accuracy of the MUSIC method is relatively higher,and the root mean square error of dual sources in low and medium reverberation(0.5s and below)is within 3°.The pseudo-intensity vector and subspace pseudo-intensity vector using the principle that the direction of acoustic energy flow is the source direction.It is supposed to be calculated based on the direction of the energy flow with a lower computational burden.The final localization error of dual sources in low and medium reverberation scenes is within 4°.2,To address the problem of localization of multiple sources in the physical location neighborhood in high reverberant environments,we propose a direct path dominance test MUSIC-group delay multi-source localization method for spherical harmonic domain to improve the resolution of adjacent sources in a reverberant environment.It is also expected to reduce the localization error due to the source location proximity and reverberant reflection.First,the frequency smoothing method is adopted in our method to focus the acoustic signal into a narrowband signal,which improves the method computational speed and reduces the sensitivity of reverberant and noise.Then the approximate W-disjoint orthogonality(assuming at most one active source exists in each time-frequency bin)is used to estimate single-source locations,thereby converting the multiple-source localization into multiple single-source localization.To improve the adjacent sources’ localization accuracy,the MUSIC-group delay spectrum is introduced to eliminate the false spectral peaks due to reverberant reflection,and thus to discriminate the sources adjacent in physical locations.Compared with direct path dominance test method,the simulation experimental results show that the localization error is reduced by 0.5° in a harsh environment(reverberation time of 0.8s and signal-to-noise ratio of5～15d B),and it is possible to locate dual sources with 15° source separation in a high reverberation environment with a localization error of about 2°.Therefore,the direct path dominance test MUSIC-group delay method proposed in this manuscript has better localization accuracy and better neighboring multi-source discrimination under high reverberation and low signal-to-noise ratio conditions.