Interaction of airborne and structure-borne noise radiated by plates

Analytical and experimental studies were undertaken in order to further the understanding of the interaction of airborne and structure-borne noise radiated by aircraft structures. The results of several measurements and computer simulations of the noise radiated by thin, isotropic, rectangular aluminum plates due to fully coherent combined acoustic and vibrational inputs is presented. The most significant finding of the study was the extremely large influence that the relative phase between the inputs has on the combined noise radiation of the plates. It is shown that phase dependent effects manifest themselves as cross terms in both the dynamic and acoustic portions of the analysis. The results show that these cross terms can radically alter the combined sound power radiated by plates constructed of aircraft-type materials. The results of the study suggest that airborne-structure-borne interactive effects could be responsible for a significant portion of the overall noise radiated by aircraft-type structures in the low frequency regime. These interactive effects have been neglected in the analyses of previous analytical and experimental studies of the interior noise of propeller driven aircraft.