Microphone array techniques using cross-correlations.
Matthew B. Rhudy, Brian A. Bucci · The Journal of the Acoustical Society of America · 2009
Civilian noise complaints and damage claims have created a need to establish a detailed record of impulse noise generated at military training facilities. Wind noise is causing false positive impulse detections in the current noise monitoring systems. Multiple channel data methods were investigated in order to distinguish the characteristics of noise events. A microphone array was used to collect four simultaneous channels of military impulse and wind noise data. Cross-correlation functions were then used to characterize the input waveforms. Three different analyses of microphone array data were developed. A new value, the min peak correlation coefficient, is defined from the minimum value of peaks of the cross-correlation coefficient functions among the different channels. This value is a measure of the likelihood that a given waveform originated from a correlated noise source. The angle of incidence of the noise source is calculated using a sound source localization technique based on the geometry of the array. A weighted averaging method was also developed to synthesize multiple channels of data into one single channel. This method preserves the correlated part of the overall signal, while reducing the effects of uncorrelated noise, such as wind.