Simple Technique for Precise Measurement of Transmission Loss of Planar Sound Waves

Abstract

A simple technique is proposed to measure the transmission loss through a panel of arbitrary size. The present technique uses two anechoic rooms to simulate the free acoustic field. Different from the conventional methods, the incident angle, the sound pressure distribution, and the spectral distribution of the incident sound waves can be changed arbitrarily. By the calibration experiments, the reasonable capabilities of the prototype facility are confirmed. In the experiment, a panel is installed in between two anechoic rooms. For the sake of simplicity, quasiplanar sound waves are provided in the sound-source room at uniform sound pressure over the panel. The intensity of the transmitted sound waves is measured in the receiving room. The modal analyses and the transmission loss measurements are completed for three different materials: aluminum, honeycomb sandwich, and carbon composite. The results are useful to verify the numerical analyses.