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Enhancement of the low frequency sou...

Lambert, Jeremy A.

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Enhancement of the low frequency sound absorption of porous materials by addition of a thin high flow-resistivity cover layer.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Enhancement of the low frequency sound absorption of porous materials by addition of a thin high flow-resistivity cover layer./
Author:	Lambert, Jeremy A.
Description:	153 p.
Notes:	Adviser: Andres Soom.
Contained By:	Masters Abstracts International45-06.
Subject:	Engineering, Aerospace. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1443989

Enhancement of the low frequency sound absorption of porous materials by addition of a thin high flow-resistivity cover layer.
Lambert, Jeremy A.

Enhancement of the low frequency sound absorption of porous materials by addition of a thin high flow-resistivity cover layer. - 153 p.

Adviser: Andres Soom.

Thesis (M.S.)--State University of New York at Buffalo, 2007.

The general performance of a porous material against a rigid backing shows very good absorption qualities at high frequencies, but at lower frequencies, where the thickness becomes much less than a wavelength of sound, the absorption is considerably reduced. Based on observations noted during outdoor sound propagation studies and published literature on layered sound absorbing structures, the addition of a thin cover with a high flow-resistivity cover layer can enhance low frequency sound absorption. The objective of this studies was to examine the possibility of increasing low frequency without significantly reducing higher frequency absorption, which usually occurs. The sound absorbing materials were modelled as porous media with complex characteristic impedance and wave number that were obtained using a single flow resistivity parameter based on a widely-used semi-empirical model due to Delany and Bazley (1971). After a thorough parametrical study, experiments were performed to validate the modelling approach, an optimisations was run in order to seek the best combination of flow resistances and layer thicknesses for a given performance requirement.Subjects--Topical Terms:

1018395
Engineering, Aerospace.

Enhancement of the low frequency sound absorption of porous materials by addition of a thin high flow-resistivity cover layer.
LDR:02075nam 2200277 a 45 001 957332
005 20110630
008 110630s2007 eng d
035 $a (UMI)AAI1443989
035 $a AAI1443989
040 $a UMI $c UMI
100 1 $a Lambert, Jeremy A. $3 1280688
245 1 0 $a Enhancement of the low frequency sound absorption of porous materials by addition of a thin high flow-resistivity cover layer.
300 $a 153 p.
500 $a Adviser: Andres Soom.
500 $a Source: Masters Abstracts International, Volume: 45-06, page: 3197.
502 $a Thesis (M.S.)--State University of New York at Buffalo, 2007.
520 $a The general performance of a porous material against a rigid backing shows very good absorption qualities at high frequencies, but at lower frequencies, where the thickness becomes much less than a wavelength of sound, the absorption is considerably reduced. Based on observations noted during outdoor sound propagation studies and published literature on layered sound absorbing structures, the addition of a thin cover with a high flow-resistivity cover layer can enhance low frequency sound absorption. The objective of this studies was to examine the possibility of increasing low frequency without significantly reducing higher frequency absorption, which usually occurs. The sound absorbing materials were modelled as porous media with complex characteristic impedance and wave number that were obtained using a single flow resistivity parameter based on a widely-used semi-empirical model due to Delany and Bazley (1971). After a thorough parametrical study, experiments were performed to validate the modelling approach, an optimisations was run in order to seek the best combination of flow resistances and layer thicknesses for a given performance requirement.
590 $a School code: 0656.
650 4 $a Engineering, Aerospace. $3 1018395
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Physics, Acoustics. $3 1019086
690 $a 0538
690 $a 0548
690 $a 0986
710 2 0 $a State University of New York at Buffalo. $3 1017814
773 0 $t Masters Abstracts International $g 45-06.
790 $a 0656
790 1 0 $a Soom, Andres, $e advisor
791 $a M.S.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1443989