An explicit scheme for wave propagation modeling of indoor environments is presented. The technique is based on the hybrid parabolic-integral equation method, which provides a correction to the parabolic equation method through a Green's function formulation. A modification of the hybrid method is proposed by the introduction of a transmission coefficient at the interfaces between different media. The iterated Crank-Nicolson scheme is used for the numerical implementation. Results confirm the superiority of the proposed technique over the existing one.