On application of radiation loss factor in the prediction of sound transmission loss of a honeycomb panel

The application of the radiation loss factor in the prediction of sound transmission loss of a lightweight, orthotropic sandwich panel is investigated in this paper. Comparisons between measurements and predicted results show that predictions often underestimate the sound transmission loss of the panel around the corresponding critical frequency when a measured loss factor, which in principle includes the radiation loss factor, is used. This is due to the methods used for the loss factor measurements and due to the fact that the band average loss factor is applied in the calculation. It is recommended to use the material loss factor measured at low frequencies plus the narrow band, theoretical radiation loss factor in order to improve the prediction of the sound transmission loss of a honeycomb panel around the critical frequency.