A methodology is presented to predict the takeoff noise benefits generated by a composite fan rotor of a high speed aircraft. The benefits are evaluated using a computer code EST/BEST (Engine Structures Technology Benefits Estimator). It estimates the benefits at the airplane level of introducing new structures technologies into existing propulsion systems. In the paper, the effect of various fan design parameters on the noise benefits are evaluated. Results obtained show that 15 percent noise reductions are realizable by making the blades from high fiber modules composites.