A Performance Study on Indirect Static Flow Resistivity Measurement Methods for Acoustic Materials

Abstract: Various empirical models have emphasized the dependence of sound absorption coefficient on static airflow resistivity, and thus its measurement becomes essential. In this paper, the two-cavity and two-thickness indirect acoustic methods are implemented based on a standard impedance tube for evaluating the static flow resistivity of foam. A comparison is made between the resistivity results obtained by the two-cavity and two-thickness method, and later validated with results of an alternating air-flow test setup which is developed as per the ISO 9053 guidelines. Further, the empirical relations are utilized to estimate the absorption coefficient from measured values of flow resistivity and are compared with measured absorption coefficient in an impedance tube. The results discussed in this study presents the feasibility and suitability of the indirect acoustic methods for evaluating the flow resistivity