Measurement Uncertainty in Random-Incidence Sound Absorption Testing: Part 2-Verification

Random-incidence sound absorption test results are not typically presented with appropriate estimates of uncertainty attached. A formulation for measurement uncertainty of random-incidence sound absorption testing per ASTM C423 was developed in Part 1. It resulted in a confidence interval on the absorption coefficient. This follow-up paper deals with the experimental verification of the uncertainty estimates in the absorption coefficient. Purposefully-designed measurement routines were executed that show the repeatability and reproducibility of three measurement schemes in various sized reverberation rooms. Results illustrate the testing methods which show agreement with the uncertainty estimates. Test reproducibility, found with roving sample position routines, agreed with the uncertainty estimates.