A centrifugal fan for ventilated rotating machinery is provided having tapered fan blades to reduce sound pressure levels generated by fan operation over a wide speed range. The tapering of the fan blades keeps the cross-sectional area of each flow channel substantially constant as the air flows radially through the fan, resulting in a less turbulent flow. Each fan blade may include a height profile having a tapered segment in which blade height decreases in proportion to increasing radial distance from the central axis of the fan.