Engine noise refers to the sounds produced by a vehicle's engine during operation. This noise can vary based on factors such as the engine type, its condition, and the vehicle's speed. Common sounds include humming, knocking, or rattling, which can indicate normal functioning or potential issues. Different types of engines, such as internal combustion engines or electric motors, produce distinct noise levels. While internal combustion engines typically generate more noise due to their mechanical components, electric motors are generally quieter. Monitoring engine noise can help identify maintenance needs and ensure optimal performance.