Mathematical model for characterizing noise transmission into finite cylindrical structures

Abstract

This work presents a theoretical study of the sound transmission into a finite cylinder under coupled structural and acoustic vibration. Particular attention of this study is focused on evaluating a dimensionless quantity, "noise reduction," for characterizing noise transmission into a small cylindrical enclosure. An analytical expression of the exterior sound pressure resulting from an oblique plane wave impinging upon the cylindrical shell is first presented, which is approximated from the exterior sound pressure for an infinite cylindrical structure. Next, the analytical solution of the interior sound pressure is computed using modal-interaction theory for the coupled structural acoustic system. These results are then used to derive the analytical formula for the noise reduction. Finally, the model is used to predict and characterize the sound transmission into a ChamberCore cylindrical structure, and the results are compared with experimental data. The effects of incidence angle and internal acoustic damping on the sound transmission into the cylinder are also parametrically studied.

Theory of compact nonporous windscreens for infrasonic measurements

“…In the case of cylindrical shells, Li and Vipperman, 2 Cheng, 6 Koval,7 and White, 8 for example, consider transmission due to the first component only and thus limit their analyses to relatively high frequencies. Tang et al, 9 on the other hand, consider both components but assume that the interior fluid is totally absorbing-a condition that does not apply to the air found inside a windscreen.…”