Development of empirical models of polyfelt fibrous materials for acoustical applications

Abstract

In this study, new empirical models for predicting the airflow resistivity, sound absorption coefficient of polyfelt fibrous materials have been developed. The empirical models were presented as simple power-relations by least square best fitting method of impedance tube and flow bench test data over a set of 14 samples. Two coefficients were identified for a new empirical formula to predict the airflow resistivity from the mass density and thickness of polyfelt materials and eight coefficients were identified for a new empirical formula to predict the characteristic acoustic impedance, propagation coefficients and sound absorption coefficient from the airflow resistivity. For the given mass density and thickness of a polyfelt fibrous material, the outcome proposed in this paper enables a quick and accurate evaluation of the acoustic properties of the material such as the airflow resistivity and sound absorption coefficient without a further requirement of flow bench and impedance tube tests. This is because that the predicted results from the new empirical models are closer to the measured results in the frequency range of interest than the other models in the previous work in the published literatures