Using Burst Excitation to obtain Acoustic Material Properties in Impedance Tubes

Abstract

Impedance tubes are a common tool used to characterize the reflection, absorption, and transmission properties of acoustic materials and structures. In this paper, we demonstrate the capability of the open-source finite element software openCFS to determine the acoustic properties of structures with gradient geometry, by using burst excitation signals in a time domain simulation setup. By decomposing the waves via a time domain approach, we obtain consistent results with the standard two and four-microphone impedance tube analyses. An in-house developed impedance tube is used to conduct experiments to verify the numerical results, deploying a feedforward control system to reproduce burst signals from a cone speaker accurately. In addition, we discuss the effects of numerical and experimental parameters on the accuracy of the results. The method offers a simplified setup to measure the acoustic properties of materials and opens up a new perspective to study materials exposed to burst excitation signals.