Enhancement of the sound absorption coefficient experimental reproducibility for different size samples

Sound absorption coefficient (SAC) measurements in a reverberation room may produce different values for different sample sizes of the same material because of the edge effect which depends on the geometrical properties of the sample. In this paper, the theory of the maximum SAC for a given size and shape of sample is extended to non-locally reacting sound absorbers to expand its application. A two-dimensional analytic strip theory is developed to calculate the value of the maximum SAC. The numerical integration method is presented and compared with the proposed analytical method and Thomasson’s tabulated results. Four different approaches are implemented to estimate the SAC of a sample using measurement on a different size sample of the same material. Results in the frequency range of 100 Hz to 10000 Hz are compared, and recommendations are given. It is shown that the proposed approach, which is a modification of a linear interpolation method, is an improved method for estimating the random SAC of a full/large size sample from measurements on a small size sample.