Spatial Processing of Urban Acoustic Wave Fields from High-Performance Computations

Future US Army ground sensors in urban terrain will process acoustic signals to detect, classify, and locate sources of interest. Optimal processing will require understanding of the effects of the urban infrastructure on sound propagation. These include multi-path phenomena that will complicate sensing, and must be accounted for in sensor placement and performance algorithms. The objective of this work is to develop spatial processing techniques for acoustic wave propagation data from three-dimensional high-performance computations to quantify scattering due to urban structures and develop reduced-order models of wave-field data. The work applies Fourier analysis to urban acoustic wave-field data to generate measures of signal fading caused by scattering. The work calculates these measures from ratios of Fourier transforms of wave-field signals with and without scattering to isolate the structure-induced scattering. In addition, we calculate impulse response functions of acoustic wave-field data, and use these functions as the input to a system realization algorithm to produce reduced-order wave-field models. The results include signal fading as functions of distance and frequency for an urban acoustic model that includes structures like those in a small-city periphery. The results also include predicted acoustic wave-field signals from reduced-order models in comparison with full-model signals. We conclude that the spatial processing of urban acoustic wave fields from high-performance computations produces broadly useful measures for understanding and modeling urban wave propagation.