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Cyphers, H. D.

Publications and source records attributed to Cyphers, H. D..

4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Comparative evaluation of predicted and measured performance of a 68-cubic meter truncated reverberant noise chamber

The performance of a medium size, truncated reverberation chamber is evaluated in detail. Chamber performance parameters are predicted, using classical acoustic theory, and are compared to results from actual chamber measurements. Discrepancies are discussed in relation to several available empirical corrections developed by other researchers. Of more practical interest is the confirmation of a recent theory stating that the present guide for the ratio of specimen volume to test chamber volume, approximately 10 percent, is overly conservative, and can be increased by a factor of at least 2 and possibly 3. Results and theoretical justification of these findings are presented.

Cyphers, H. D.↗
NASA NTRS1974

The use of large cylindrical enclosures as a cost effective approach to reverberant acoustic testing

The feasibility of using existing cylindrical enclosures as cost effective substitutes for reverberant acoustic test chambers is investigated. In particular the performance of two large cylindrical environmental chambers, 1400 and 14,000 cu m in volume, is evaluated in detail. Reverberant acoustic chamber characteristics are predicted using classical acoustic theory and are compared to results obtained from actual chamber measurements. A method of scaling low level test results to predict the performance of a particular driver/horn/chamber configuration is also discussed. This prediction technique is confirmed by actual test data using a 200 kilowatt acoustic generator.

On, F. J.↗