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Papers by Keith Attenborough

Research paper thumbnail of Point to point propagation over periodic rough boundaries

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Research paper thumbnail of Noise Reduction by Greening

Academia Engineering, Aug 24, 2023

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Research paper thumbnail of Pioneering study of outdoor sound propagation

Journal of the Acoustical Society of America, May 1, 2022

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Research paper thumbnail of Acoustics of Rigid–Porous Materials

PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO. eBooks, Dec 1, 2004

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Research paper thumbnail of Sound Propagation in the Atmosphere

Springer eBooks, 2007

... The pressure at the receiver is the sum of four terms that correspond to the sound paths SgER... more ... The pressure at the receiver is the sum of four terms that correspond to the sound paths SgERg, Si ERg, SgERi, and SiERi. ... For example, the diffracted wave along the path SgERg would be given by P1 = Att1ei[k(r0+rr )+π/4] (20) ...

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Research paper thumbnail of A pocket-sized introduction to dynamics

HAL (Le Centre pour la Communication Scientifique Directe), 2008

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Research paper thumbnail of Measurements and predictions of hooded crow (<i>Corvus corone cornix</i>) call propagation over open field habitats

Journal of the Acoustical Society of America, 2008

In a study of hooded crow communication over open fields an excellent correspondence is found bet... more In a study of hooded crow communication over open fields an excellent correspondence is found between the attenuation spectra predicted by a “turbulence-modified ground effect plus atmospheric absorption” model, and crow call attenuation data. Sound propagation predictions and background noise measurements are used to predict an optimal frequency range for communication (“sound communication window”) from an average of crow call spectra predicted for every possible combination of the sender/receiver separations 300, 600, 900, and 1200m and heights 3,6,9m thereby creating a matrix assumed relevant to crow interterritorial communication. These predictions indicate an optimal frequency range for sound communication between 500Hz and 2kHz. Since this corresponds to the frequency range in which crow calls have their main energy and crow hearing in noise is particularly sensitive, it suggests a specific adaptation to the ground effect. Sound propagation predictions, together with background noise measurements and hearing data, are used to estimate the radius of the hooded crow active space. This is found to be roughly 1km in moderately windy conditions. It is concluded that the propagation modeling of the sort introduced here could be used for assessing the impact of human noise on animal communication.

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Research paper thumbnail of Manufacturing, modeling, and experimental verification of slitted sound absorbers

Designs with uniformly distributed slits normal or inclined to the incident surface exhibit a gre... more Designs with uniformly distributed slits normal or inclined to the incident surface exhibit a great potential because of their simplicity and good acoustical performance. However, production of materials of this sort is challenging as the required fabrication precision is very high. This paper deals with additive manufacturing, modeling, and impedance tube testing of a few slitted geometries and their variations, including cases where the dividing walls between slits are perforated. They were designed to be producible with current 3D printing technology and provide reliable measurements using standardized equipment. The normal incidence sound absorption curves predicted analytically and numerically were verified experimentally. It is observed that such simple configurations may lead to absorption properties comparable to porous acoustic treatments with more complex microstructure. The good agreement between the predictions and measurements supports the validity of the multi-scale modeling employed

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Research paper thumbnail of Effects of surface roughness on outdoor acoustics

한국소음진동공학회 국제학술발표논문집, Aug 1, 2003

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Research paper thumbnail of ACOUSTICS2008/151 Accelerometer measurements of acoustic-to-seismic coupling above buried objects

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Research paper thumbnail of Using a fast Fourier method to model sound propagation in a stratified atmosphere over a stratified porous-elastic ground

ABSTRACT

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Research paper thumbnail of Sound dissipation in porous media

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Research paper thumbnail of Student-based surveys of noise levels around and inside dwellings in the United Kingdom

Journal of Sound and Vibration, Jul 1, 1989

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Research paper thumbnail of Propagation from a point source over a porous and elastic foam layer

Applied Acoustics, 1993

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Research paper thumbnail of Acoustical Surveying of Porous Soils

Springer eBooks, 1985

Studies of outdoor sound propagation, particularly at near grazing-incidence and of the phenomeno... more Studies of outdoor sound propagation, particularly at near grazing-incidence and of the phenomenon of acoustic-to-seismic coupling have motivated a search for suitable models for the acoustical characteristics of outdoor ground surfaces. In many instances of outdoor propagation, it has been found possible to obtain sufficient accuracy by assuming both that the ground is locally-reacting, so that it may be described by its normal surface impedance (Zs), and, by calculating Zs from empirical power law relationships for the characteristic impedance of fibrous absorbents1. These relationships introduce a single parameter, the flow resistivity of the surface. The range of validity of these empirical relationships was stated by their authors to be 0.01 < (fΩo/Rs) < 1; where f is the frequency in Hz, Ωo is the equilibrium density or air in Kg m -3 and Rs is the flow resistivity in N s m-4. Moreover the relationships were derived from data for dry fibrous materials with porosities near unity and flow resistivities ranging from 5000 to 80000 N s m-3. Despite this, the relationships have been used successfully in combination with well-established theory for propagation from a point source above an impedance boundary to describe excess attenuation, up to 1000 Hz, over short ranges encompassing a wide variety of ground surfaces outdoors 2. The single parameter that, consequently, describes the acoustical behaviour of the ground has been called the effective flow resistivity (Rse).

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Research paper thumbnail of Models for the acoustic characteristics of porous road surfaces

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Research paper thumbnail of The influence of operationalfactors on aircraft noise levels

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Research paper thumbnail of Comment on ‘Application of noise guidance to the assessment of industrial noise with character on residential dwellings in the UK’, D. Baker 93 (2015) 88–96

Applied Acoustics, 2019

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Research paper thumbnail of Acoustic determination of air‐filled porosity and relative air permeability of soils

Journal of Soil Science, 1992

SUMMARYTwo acoustic techniques for determining the air‐filled porosity and air permeability of so... more SUMMARYTwo acoustic techniques for determining the air‐filled porosity and air permeability of soil surfaces, and the near‐surface variation of these properties with depth, have been applied to several soils in situ. The techniques depend upon an inversion process using data on sound propagation near to the soil surface and through the soil surface. The measured difference in acoustic spectra received by two vertically separated microphones above the ground surface and by probe microphones beneath the surface were matched theoretically to deduce the porosity of air‐filled connected pores and an effective air permeability which depends on pore shape and size distribution. This modified permeability parameter and the acoustically deduced porosity varied realistically with surface sealing and compaction. The acoustically deduced porosities were within 10% of those obtained conventionally. Changes in acoustically deduced parameters occurred with changes in moisture content both in soil ...

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Research paper thumbnail of Experiments on nonlinear acoustic detection of objects buried in sand

Proceedings of the Interntional Congress on Ultrasonics, 2007

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Research paper thumbnail of Point to point propagation over periodic rough boundaries

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Research paper thumbnail of Noise Reduction by Greening

Academia Engineering, Aug 24, 2023

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Pioneering study of outdoor sound propagation

Journal of the Acoustical Society of America, May 1, 2022

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Acoustics of Rigid–Porous Materials

PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO. eBooks, Dec 1, 2004

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Sound Propagation in the Atmosphere

Springer eBooks, 2007

... The pressure at the receiver is the sum of four terms that correspond to the sound paths SgER... more ... The pressure at the receiver is the sum of four terms that correspond to the sound paths SgERg, Si ERg, SgERi, and SiERi. ... For example, the diffracted wave along the path SgERg would be given by P1 = Att1ei[k(r0+rr )+π/4] (20) ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A pocket-sized introduction to dynamics

HAL (Le Centre pour la Communication Scientifique Directe), 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Measurements and predictions of hooded crow (<i>Corvus corone cornix</i>) call propagation over open field habitats

Journal of the Acoustical Society of America, 2008

In a study of hooded crow communication over open fields an excellent correspondence is found bet... more In a study of hooded crow communication over open fields an excellent correspondence is found between the attenuation spectra predicted by a “turbulence-modified ground effect plus atmospheric absorption” model, and crow call attenuation data. Sound propagation predictions and background noise measurements are used to predict an optimal frequency range for communication (“sound communication window”) from an average of crow call spectra predicted for every possible combination of the sender/receiver separations 300, 600, 900, and 1200m and heights 3,6,9m thereby creating a matrix assumed relevant to crow interterritorial communication. These predictions indicate an optimal frequency range for sound communication between 500Hz and 2kHz. Since this corresponds to the frequency range in which crow calls have their main energy and crow hearing in noise is particularly sensitive, it suggests a specific adaptation to the ground effect. Sound propagation predictions, together with background noise measurements and hearing data, are used to estimate the radius of the hooded crow active space. This is found to be roughly 1km in moderately windy conditions. It is concluded that the propagation modeling of the sort introduced here could be used for assessing the impact of human noise on animal communication.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Manufacturing, modeling, and experimental verification of slitted sound absorbers

Designs with uniformly distributed slits normal or inclined to the incident surface exhibit a gre... more Designs with uniformly distributed slits normal or inclined to the incident surface exhibit a great potential because of their simplicity and good acoustical performance. However, production of materials of this sort is challenging as the required fabrication precision is very high. This paper deals with additive manufacturing, modeling, and impedance tube testing of a few slitted geometries and their variations, including cases where the dividing walls between slits are perforated. They were designed to be producible with current 3D printing technology and provide reliable measurements using standardized equipment. The normal incidence sound absorption curves predicted analytically and numerically were verified experimentally. It is observed that such simple configurations may lead to absorption properties comparable to porous acoustic treatments with more complex microstructure. The good agreement between the predictions and measurements supports the validity of the multi-scale modeling employed

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effects of surface roughness on outdoor acoustics

한국소음진동공학회 국제학술발표논문집, Aug 1, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of ACOUSTICS2008/151 Accelerometer measurements of acoustic-to-seismic coupling above buried objects

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Using a fast Fourier method to model sound propagation in a stratified atmosphere over a stratified porous-elastic ground

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Sound dissipation in porous media

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Student-based surveys of noise levels around and inside dwellings in the United Kingdom

Journal of Sound and Vibration, Jul 1, 1989

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Propagation from a point source over a porous and elastic foam layer

Applied Acoustics, 1993

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Acoustical Surveying of Porous Soils

Springer eBooks, 1985

Studies of outdoor sound propagation, particularly at near grazing-incidence and of the phenomeno... more Studies of outdoor sound propagation, particularly at near grazing-incidence and of the phenomenon of acoustic-to-seismic coupling have motivated a search for suitable models for the acoustical characteristics of outdoor ground surfaces. In many instances of outdoor propagation, it has been found possible to obtain sufficient accuracy by assuming both that the ground is locally-reacting, so that it may be described by its normal surface impedance (Zs), and, by calculating Zs from empirical power law relationships for the characteristic impedance of fibrous absorbents1. These relationships introduce a single parameter, the flow resistivity of the surface. The range of validity of these empirical relationships was stated by their authors to be 0.01 < (fΩo/Rs) < 1; where f is the frequency in Hz, Ωo is the equilibrium density or air in Kg m -3 and Rs is the flow resistivity in N s m-4. Moreover the relationships were derived from data for dry fibrous materials with porosities near unity and flow resistivities ranging from 5000 to 80000 N s m-3. Despite this, the relationships have been used successfully in combination with well-established theory for propagation from a point source above an impedance boundary to describe excess attenuation, up to 1000 Hz, over short ranges encompassing a wide variety of ground surfaces outdoors 2. The single parameter that, consequently, describes the acoustical behaviour of the ground has been called the effective flow resistivity (Rse).

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Models for the acoustic characteristics of porous road surfaces

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The influence of operationalfactors on aircraft noise levels

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Comment on ‘Application of noise guidance to the assessment of industrial noise with character on residential dwellings in the UK’, D. Baker 93 (2015) 88–96

Applied Acoustics, 2019

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Acoustic determination of air‐filled porosity and relative air permeability of soils

Journal of Soil Science, 1992

SUMMARYTwo acoustic techniques for determining the air‐filled porosity and air permeability of so... more SUMMARYTwo acoustic techniques for determining the air‐filled porosity and air permeability of soil surfaces, and the near‐surface variation of these properties with depth, have been applied to several soils in situ. The techniques depend upon an inversion process using data on sound propagation near to the soil surface and through the soil surface. The measured difference in acoustic spectra received by two vertically separated microphones above the ground surface and by probe microphones beneath the surface were matched theoretically to deduce the porosity of air‐filled connected pores and an effective air permeability which depends on pore shape and size distribution. This modified permeability parameter and the acoustically deduced porosity varied realistically with surface sealing and compaction. The acoustically deduced porosities were within 10% of those obtained conventionally. Changes in acoustically deduced parameters occurred with changes in moisture content both in soil ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Experiments on nonlinear acoustic detection of objects buried in sand

Proceedings of the Interntional Congress on Ultrasonics, 2007

Bookmarks Related papers MentionsView impact