The resonant sound transmission has been regarded to be negligible in finite single partitions compared to the non-resonant transmission. In this study, the sound transmission coefficient is reconsidered by using the general modal expansion method in order to estimate the contribution of resonant components to the whole sound transmission at frequency bands below the coincidence frequency. By investigating the band-average difference between the total and non-resonant transmission losses, the validity of the aforementioned assumption is discussed. In the analysis, the participation factor comprised of size, thickness, and loss factor is employed. Based on this factor, the valid range of neglecting the resonant sound transmission is proposed, in which the inclusion of the resonant component makes difference being less than 1 dB. (C) 2003 Elsevier Ltd. All rights reserved.