Yes, in most installations increasing the number of blades helps to reduce noise. Cockpit noise comes from a variety of sources; engine, exhaust, air flow around the fuselage, and the propeller. Vibrations are also perceived as noise in the cockpit. In a single-engine airplane, the propeller blade wake will beat on the windshield producing noise. A 2-blade propeller produces two pressure pulses per revolution, where a 3-blade propeller will produce three smaller pulses per revolution (for the same amount of total thrust) which is inherently smoother and therefore quieter. The 3-blade propeller will generally have a smaller diameter than the 2-blade propeller that it replaces, which also reduces the tip speed and noise. In a twin-engine aircraft, the reduced diameter of the 3- blade propeller will result in less tip-generated noise and a greater clearance between the blade tip and the fuselage. Both of these characteristics will reduce cabin noise. - See more at:
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