Attenborough, Keith; Bashir, Imran and Taherzadeh, Shahram
Due to copyright restrictions, this file is not available for public download
Click here to request a copy from the OU Author.
|DOI (Digital Object Identifier) Link:||http://dx.doi.org/doi:10.1121/1.3569740|
|Google Scholar:||Look up in Google Scholar|
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|
|Funders:||EC FP7 HOSANNA|
|Keywords:||acoustic impedance; acoustic wave absorption; asphalt; porous materials|
|Academic Unit/Department:||Mathematics, Computing and Technology > Design, Development, Environment and Materials|
|Depositing User:||Users 8259 not found.|
|Date Deposited:||23 May 2011 08:12|
|Last Modified:||10 Dec 2012 22:09|
Actions (login may be required)
|Public: Report issue / request change|