An acoustic baffle for reducing noise of a centrifugal fan includes a base for mounting with a fan outlet and a projection extending from the length of the base at a back side of the base and curving away from a top surface of the base. The projection continuously tapers from the base to an apex that aligns with a center line of the base. The projection extends over the fan wheel and tapers from left and right sides of the outlet to a fan tangency point at a midpoint of the outlet and aligned with the apex, when the acoustic baffle is installed in the outlet. The acoustic baffle effects a gradual variation in radial and tangential airflow at the blower outlet, to reduce fan blade passage tone.