Study of ASTM C423 Repeatability and Reproducibility

The bulk sound absorption is a critical characteristic of acoustic materials and systems.  Determination of this characteristic can be performed utilizing ASTM C423:  Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method.  Most manufacturers of acoustic materials publish data determined utilizing this standard.  As users select materials for projects the competition for the highest performance may drive them to choose between products with very similar results.  This brings the question of what differential in performance can be identified as significant.  A study was initiated to gather data on a single reference specimen from multiple laboratories and compare results to those in the precision and bias statement in the standard which was last updated in 2001.  The results of the study are presented in this paper.