Copie van een youtube reply ("tractor" is een propeller voorop het toestel):
Tractor gets a clean undisturbed column air to bite into, and loses just a little thrust to air deceleration against the airframe. Pushers have to constantly "chop" through irregular air which is coming off the back of the wing, fuselage, etc. So the effective angle of attack of the prop blades is constantly changing as the prop moves through its arc, which contains air moving at different speeds. This causes the buzzing noise and a loss of efficiency.