Acoustical models and measurements treating the ground as a rigid porous medium

Keith Attenborough

doi:10.1117/12.396289

22 August 2000 Acoustical models and measurements treating the ground as a rigid porous medium

Keith Attenborough

Proceedings Volume 4038, Detection and Remediation Technologies for Mines and Minelike Targets V; (2000) https://doi.org/10.1117/12.396289
Event: AeroSense 2000, 2000, Orlando, FL, United States

Abstract

If the ground is assumed to be rigid and porous, then classical porous material models may be used. Parameters such as flow resistivity, porosity, tortuosity, viscous and thermal characteristic dimensions or power size distribution are found to be necessary for the acoustic description of rigid porous materials. Typical values of ground flow resistivity are relatively high and permit simple approximations. The expressions for wave number, attention and surface impedance that result from this type of approach are presented and discussed. If the ground may be treated as an impedance plane then classical theory may be used to describe the field due to a point source above the ground. The results of this theory are described. It enables measurements made at a receiver close to the ground of the sound spectrum due to a nearby broad-band point source to be used to deduce the ground impedance. The free field spectrum due to the source or the field received at another vertically-separated receiver is used as a reference. The influences of layering within the ground and small-scale roughness on the surface are discussed together with the area of the ground involved for a given source-receiver geometry. Results of boundary element modeling of the influence of a buried object on excess attenuation spectra and the feasibility of using acoustic impedance deduction for mine detection are reviewed.

Citation Download Citation

Keith Attenborough "Acoustical models and measurements treating the ground as a rigid porous medium", Proc. SPIE 4038, Detection and Remediation Technologies for Mines and Minelike Targets V, (22 August 2000); https://doi.org/10.1117/12.396289

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