Forward and reverse transmission loss measurements

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ConferenceInter-Noise 2004: 22 August 2004, Prague, Czech Republic
Pages16; # of pages: 6
SubjectSound transmission & insulation
AbstractAccording to the simple theory underlying measurements of sound transmission loss, it should not matter which of the two rooms is selected as the source room; the sound fields are assumed to be diffuse. In practice, different values of sound transmission loss are measured when the roles of the rooms are reversed. The differences exceed the repeatability limits for the test and are seen throughout the frequency range for standard testing. These differences can give rise to two different single number ratings ? STC or Rw ? for the same structure tested in a single laboratory. No criteria are given in standard test methods for selecting which room is the source when testing normal walls and floors. The solution proposed here is that standards should require testing in both directions. Differences at low frequencies can be attributed to modal responses of the rooms and the specimen. No explanation for the differences at high frequencies has been found.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number47035
NPARC number20377539
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Record identifierc13b945b-1b00-48ca-bb86-db345f28bf65
Record created2012-07-24
Record modified2016-05-09
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