Static flow resistivity measurements based on the ISO 10534.2 standard impedance tube

Abstract

Static flow resistivity is a fundamental parameter governing the sound absorption behavior of different materials, and several methods based on the use of impedance tubes have been developed for measuring the flow resistivity acoustically. However, these methods cannot be directly implemented in the standard impedance tubes that are widely used for measurements of sound absorption coefficients and impedance as defined in ISO 10534.2, because the termination conditions of impedance tubes and the placement of microphones in these existing methods are different. In this paper, a new acoustic method based on the impedance transfer function is proposed to determine the static flow resistivity with a standard impedance tube that complies with ISO 10534.2. The accuracy and the robustness of the proposed method are investigated through the finite element analysis and the feasibility of determining the static flow resistivity is validated through experiments. It is found that the accuracy of the proposed method is sensitive to the acoustic center position of the measurement microphones and the accuracy can be enhanced by increasing the back cavity depth or decreasing the measurement frequency.