HORNER, J.L. and PEAT, K.S., 2011. Higher mode sound transmission from a point source through a rectangular aperture. Journal of the Acoustical Society of America, 129(1), pp. 5-11
This paper considers the higher-order scattered and transmitted wave fields that result when an acoustic
wave from a point source impinges at an arbitrary angle on a rectangular aperture in a rigid, thick
wall. In this analysis, it is assumed that free field conditions exist on both sides of the aperture.
Although the full scattered and transmitted pressure fields contain both modal sum and modal coupling
effects, the modal coupling effects of the higher-order modes are ignored such that an approximate
analytical solution to the uncoupled analysis can be utilized. Experiments have been undertaken
to measure the sound pressure levels in the transmitted field that result when sound from a point
source impinges on the opposite side of a rectangular aperture. Measurements were made with the
source located at the required position to drive a particular in-aperture higher-order mode. The source
was also located at positions that did not directly excite any in-aperture higher-order mode at a cut-on
frequency. These results indicate that the approximate analysis developed here gives accurate solutions
whether or not any mode of the aperture is driven at cut-on. Thus, the method can be used for
any relative location of a source from a rectangular aperture of any dimensions.