Which part of the engine produces the most dominant noise?

• A. Fan and Turbine
• B. Combustor
• C. Accessory Gearbox
• D. Nacelle

Answer: (A)

In turbofan engines, the loudest sound comes from how the engine moves air. The fan handles a huge volume of air and creates strong pressure fluctuations as the blades pass by and accelerate air through the duct. Those fluctuations generate the majority of the engine’s audible noise, especially at takeoff and climb.

The turbine also contributes to the overall noise, mainly from the exhaust path and rotor interactions in the hot section. While it adds, the fan’s noise is the dominant component, and the turbine’s contribution is significant enough that describing the main noise sources as both fan and turbine best fits how the engine sounds in operation.

The combustor adds high-frequency noise, but its overall level is typically smaller than the fan’s. The accessory gearbox and nacelle aren’t primary noise sources; the gearbox is relatively quiet in comparison, and the nacelle mainly shapes and shields noise rather than generating it.