Coping with uncertainties in the design and evaluation of acoustical assemblies

Abstract

The statistical uncertainty in acoustical testing has been insufficiently studied in the acoustical community, and the effects of the uncertainties have been largely ignored. Most acousticians do not know what the reproducibility limit is for acoustical test results from accredited laboratories, but tacitly assume that the limits are on the order 1 or 2 rating points. In recent years the authors have demonstrated that the uncertainties in acoustical laboratory testing in the United States are much higher than most people have realized [LoVerde and Dong, J. Acoust. Soc. Am. 125, 2629 (2009), J. Acoust. Soc. Am. 126, 2171 (2009) J. Acoust. Soc. Am. 130, 2355 (2011)]. The typical acoustician's reaction is that it should be possible to measure to higher precision with suitable changes to the test methodology, and improving the precision of laboratory testing is an important goal that deserves much more attention than it has received. However, there is no guarantee that it will be practical to substantially decrease the uncertainties in acoustical testing, and regardless, the uncertainties characterizing the existing body of research cannot be changed. Accepting this fact demands some changes to how acoustical consultants design assemblies, evaluate products, and interact with clients and regulatory agencies.