Determining the transmission loss of varia-ble cross-section apertures

Minimizing the transmission of sound through leaks is central to enclosure and barrier design. In the current work, a transfer matrix method is used to predict the transmission loss of leaks assuming that the cross-sectional dimensions of the leak are small compared to an acoustic wavelength. The approach used can be applied to leaks of any shape and special consideration is given to apertures with varying cross-section. Reactive strategies like Helmholtz resonators and abrupt area changes are considered to reduce the sound transmission. For larger openings, an acoustic finite element strategy is suggested. The boundary condition on the source side is a diffuse field applied by determining the cross-spectral force matrix of the excitation. At the termination, the radiation impedance is calculated using a wavelet algorithm. Simulation results using the transfer matrix and finite element approaches agree with published results and demonstrate good agreement with one other.