A coupled RCAS/PSU-WOPWOP analysis has been implemented to investigate the aerodynamic and acoustic impact of propeller-wing interference. A nominal RCAS model based on XV-15 vehicle is developed first. The unsteady propeller blade loading due to the interference has been validated with another study using high fidelity CFD simulation. The capability of the coupled RCAS/PSU-WOPWOP analysis for noise prediction has been validated against measured acoustic flight test data of XV-15 tiltrotor vehicle. The impact of the impulsive unsteady propeller loads on noise has been investigated. The results show that propeller unsteady loading can add more than 10 dB in OASPL level. Parametric studies have also been conducted. The results show that lowering propeller RPM may slightly reduce the noise level, but the unsteady propeller loading can add more than 10 dB in OASPL. The unsteady loading effect is even more significant when the vehicle speed is reduced, the OASPL level at the rear of propellers may be increased by 20 dB.