An experimental transfer matrix method to characterize acoustic materials at high sound pressure levels in airflow environment

Abstract

A transfer matrix method is proposed for experimental characterization of acoustic materials in the presence of airflow at high sound pressure levels. This method uses two experimental measurements with two different termination loads under flow to derive the transfer matrix coefficients of the tested material. The acoustic pressure and velocity fields upstream and downstream of the material are decomposed into forward and backward traveling waves. Complex models of the wavenumbers are used to account for the damping effect of acoustic waves in the presence of turbulent flow. The components of the transfer matrix of the material are given as function of the pressures and velocities at both faces of the material, which are obtained from the two measurements. The proposed method is validated by comparison with two-source method for different experimental measurements with airflow at high sound pressure levels up to 150 dB and good agreements are obtained. Thus, the proposed method can be used to estimate experimentally the acoustic properties of materials at higher sound pressure excitations in the presence of airflow.