Abstract:

Previous papers by the authors addressed the analytical derivation and the numerical implementation of a lumped parameter model for the acoustic power output of a vibrating structure. Here the experimental measurement of the resistance is addressed. The acoustic resistance, which is related to the Green's function of the second kind, can be determined experimentally by: (1) constructing an acoustically hard physical model of the boundary surface; (2) representing the discrete simple source with a small loudspeaker; and (3) measuring the acoustic field at a receiver location with a small microphone. The design of an acoustic resistance probe is described, along with an analysis of both the calibration procedure and the subsequent calculation of the resistance matrix. The analysis is validated through several example problems, with the accuracy of the measured acoustic resistance assessed by direct comparison to analytical or numerical solutions. For most of the cases considered, the experimental measurements and numerical predictions agree very well, but for some of the example problems discrepancies occur due to the limited dynamic range of the probe and acoustic excitation of structural vibrations.