Title
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Absorption measurement of acoustic materials using a scanning laser Doppler vibrometer
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Author
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Abstract
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In this article a method is proposed to estimate the normal incidence reflection ratio and absorption coefficient of acoustical materials using measurements in a transparent tube excited with a loudspeaker and terminated with the material under investigation. The waveforms are measured at different locations in the tube using a scanning laser Doppler vibrometer. Because the measurement probe (i.e., the laser beam) does not interfere with the wave in the tube, narrow tubes can be used. This means that-in contrast to the standardized wide tube tests using microphones-the proposed experiment could be used for high frequencies (in the paper an 8 mm tube was used, resulting in a 25 kHz upper frequency limit). It is shown based on theoretically known scenarios (i.e., an open tube and a rigid termination) that the absorption coefficient can be obtained with an error of about three percent. In addition, the absorption coefficient of two commonly used absorption materials-glass fiber wool and carpet-were determined and found to be in good agreement with material databases. (c) 2005 Acoustical Society of America. |
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Language
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English
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Source (journal)
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The journal of the Acoustical Society of America. - New York, N.Y., 1929, currens
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Publication
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New York, N.Y.
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2005
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ISSN
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0001-4966
[print]
1520-8524
[online]
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DOI
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10.1121/1.1859233
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Volume/pages
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117
:31
(2005)
, p. 1168-1172
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ISI
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000227574700019
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Full text (Publisher's DOI)
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