Final answer:
A propeller synchrophasing system reduces noise and vibration by adjusting the rotational speed of multiple propellers on an aircraft.
Step-by-step explanation:
A propeller synchrophasing system allows a pilot to reduce noise and vibration by adjusting the rotational speed of multiple propellers on an aircraft. By synchronizing the rotational speeds of the propellers, the system minimizes the interference of sound waves produced by each propeller, resulting in reduced noise and vibration.