This paper describes a simple one-dimensional predictive model for breakout noise from a thin rectangular duct with different end conditions like anechoic termination, rigid-end, and open-end termination. This model incorporates acoustic reflection effects in the duct internal sound field by using standing wave pattern with the transfer matrix approach. The coupling phenomenon is modelled making use of a common axial wave number for acoustic waves inside and flexural waves in the walls of the duct. The noise radiated from the rectangular duct is modelled as a finite-length line source. This standing wave analytical model has been compared with numerical model, the corresponding progressive wave model, and experimental results available in the literature. The effect of coupling in acoustic modes and flexural modes has been discussed.