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| Title: |
A method for reducing ground reflection effects from acoustic measurements
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| Author(s): |
Noerager, J. A.; Rice, E. J.; Feiler, C. E.
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| Abstract: |
The method involved placing foam blocks on the ground between sound source and receiver in an approximation of the wedges in an anechoic chamber. The tests were performed out of doors as a function of the receiver height and source-receiver separation distance. The spacing between blocks and the extent of ground covered were varied to estimate the optimum placement and minimum amount of foam treatment needed. Base-line tests without foam were also performed. It was found that the foam treatment reduced the amplitude of the peaks and valleys in the sound pressure spectra substantially. The foam was least effective at low frequency, especially for the low receiver height and for large source-receiver distances. Results from the base-line tests were compared with theoretically predicted results. These base-line test results were in reasonable agreement with those from theory.
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| NASA Center: |
Glenn Research Center
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| Publication Date: |
Mar 1, 1972
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| Document Source: |
CASI |
| Online Source: |
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| Document ID: |
19720012091
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| Accession ID: |
72N19741
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| Publication Information: |
Number of Pages = 69 |
| Report Number: |
E-6573; NASA-TN-D-6666
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| Contract-Grant-Task Number: |
RTOP 132-80 |
| Price Code: |
A04 |
| Keywords: |
ACOUSTIC MEASUREMENT; POLYURETHANE FOAM; REFLECTION; ABSORPTION; EFFECTIVENESS; GRAPHS (CHARTS);
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| Accessibility: |
Unclassified; No Copyright; Unlimited; Publicly available; |
| Updated/Added to NTRS: |
2005-08-25 |
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