• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1675-1680
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• 2000

Recently the uncertainty has been made rapid progress in various fields of industry but the uncertainty measurement method of acoustical test (i.e. Insertion loss, Absorption ratio, Transmission loss etc,) hasn't been established. In this study, the uncertainty of measurement method for ducted silencers is carried out according to ISO 7235. The standard uncertainty factors are composed of sound pressure level, microphone sensitivity and pistonphone calibration in this measurement. Sound pressure level is type A evaluation of uncertainty, microphone sensitivity and pistonphone calibration are type B evaluation of uncertainty. The combined standard uncertainty is calculated by two type evaluation. The expanded uncertainty is expressed by the combined standard uncertainty multiply k value which is yield the effective degree of freedom.

• The Journal of the Acoustical Society of Korea
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• v.22 no.6
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• pp.463-471
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• 2003

The results of the APMP (Asia Pacific Metrology Programme) regional intercomparison of acoustic calibrators were reviewed and analyzed. The artefacts used in intercomparison are a sound level calibrator and a pistonphone. The microphones used to measure the output pressure level are 1" and 1/2" standard microphones (LS1P, LS2P) as well as 1" and 1/2" reference microphones (WS1P/F, WS2P/F). The results obtained using standard microphones are satisfactory, but those obtained by the reference microphones, even though E/sub n/ values are within ±1.0, showed great deviations. Such results had come from the inaccurate calibration of reference microphones. By using the correct calibration results which were obtained by the recently established international standards, the new results were very similar to those of the foreign standard institutes.