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Outdoor ground impedance models

Attenborough, Keith; Bashir, Imran and Taherzadeh, Shahram (2011). Outdoor ground impedance models. Journal of the Acoustical Society of America, 129(5) pp. 2806–2819.

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URL: http://asadl.org/jasa/resource/1/jasman/v129/i5/p2...
DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1121/1.3569740
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Abstract

Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed- layer version of the slit-pore model gives the most reasonable parameter values.

Item Type: Journal Article
Copyright Holders: 2011 Acoustical Society of America
ISSN: 0001-4966
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNot SetEC FP7 HOSANNA
Keywords: acoustic impedance; acoustic wave absorption; asphalt; porous materials
Academic Unit/Department: Mathematics, Computing and Technology > Engineering & Innovation
Mathematics, Computing and Technology
Interdisciplinary Research Centre: eSTEeM
Item ID: 28793
Depositing User: Users 8259 not found.
Date Deposited: 23 May 2011 08:12
Last Modified: 05 Mar 2014 17:00
URI: http://oro.open.ac.uk/id/eprint/28793
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