title: Uncertainty analysis of standardized measurements of random-incidence absorption and scattering coefficients.
abstract: This work presents an analysis of the effect of some uncertainties encountered when measuring absorption or scattering coefficients in the reverberation chamber according to International Organization for Standardization/American Society for Testing and Materials standards. This especially relates to the uncertainty due to spatial fluctuations of the sound field. By analyzing the mathematical definition of the respective coefficient, a relationship between the properties of the chamber and the test specimen and the uncertainty in the measured quantity is determined and analyzed. The validation of the established equations is presented through comparisons with measurement data. This study analytically explains the main sources of error and provides a method to obtain the product of the necessary minimum number of measurement positions and the band center frequency to achieve a given maximum uncertainty in the desired quantity. It is shown that this number depends on the ratio of room volume to sample surface area and the reverberation time of the empty chamber.
authors.affiliation: Institute of Technical Acoustics, RWTH Aachen University, Kopernikusstrasse 5, 52074 Aachen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Müller-Trapet
authors.affiliation: Institute of Technical Acoustics, RWTH Aachen University, Kopernikusstrasse 5, 52074 Aachen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Vorländer