What are the causes of noise in motor vehicles?

[Graham]

Here is a related introduction to the causes of engine noise: 1. Intake system noise: High-speed gas flows through the air filter, intake pipe, and valve into the cylinder, generating strong aerodynamic noise during the process. Engine noise is mainly transmitted into the cabin through the front fender, engine hood firewall, and exhaust pipe. 2. Road noise: Road noise is formed when the vehicle cuts through the wind at high speeds, and it is also generated by the vibration of the chassis caused by driving. Additionally, gravel hitting the vehicle's chassis produces road noise. Road noise is mainly transmitted into the cabin through the four doors, trunk, front and rear fenders, and front wheel arches. 3. Tire noise: Tire noise is generated by the friction between the tires and the road surface during high-speed driving. The level of tire noise depends on the road conditions and tire tread—the worse the road conditions, the greater the tire noise. Moreover, there is a significant difference in tire noise between asphalt and concrete roads. It is mainly transmitted through the trunk and front and rear fenders.

[OArianna]

As someone who frequently repairs cars, I think there are many sources of car noise. The most common is engine issues, such as when the pistons are worn or there's insufficient oil, the engine will hum loudly; if the exhaust system is cracked or the muffler is broken, driving will produce a popping noise; uneven tire tread or aging tires can create a whistling sound at high speeds, which is very uncomfortable; a loose suspension or worn drive shaft will squeak when going over bumps; thin brake pads will produce a sharp screech. These noises are not only annoying but may also affect driving safety. I suggest car owners regularly check the belts and lubrication system to ensure the vehicle is balanced, which can reduce unnecessary noise. Older cars are especially prone to problems, so frequent maintenance can extend the lifespan of parts and keep driving quiet.

[RobertMarie]

I drive to and from work every day, and the noise really affects my mood. My old car had this issue: when the tire pressure was low or the tires were severely worn, road noise increased significantly; the engine would roar when accelerating, possibly due to carbon buildup on the spark plugs; a loose exhaust pipe connection caused vibrations and strange noises in the rear section; and wind noise was particularly noticeable at high speeds, making the entire cabin buzz. These issues not only made me tired but also drew complaints from neighbors about the disturbance. I found that switching to better tires and regularly changing the oil significantly reduced noise. Additionally, keeping the window seals intact helps, and the fan noise is lower in hot weather. In short, simple maintenance can make commuting much quieter.

[MacAlan]

When modifying cars, I noticed a lot of noise comes from the exhaust system or improper engine tuning. For example, a broken exhaust pipe or unstable connection causes a roaring sound during acceleration; if the engine is unbalanced after modification, it rattles at idle; poor tire grip squeals when cornering, ruining the fun; and aging suspension bushings make dull thuds over speed bumps. This not only disturbs others but can also lead to fines. Regular checks for loose belts or stuck fans can reduce noise. Starting the car on rainy days tends to be louder, and cleaning the throttle body often helps. Maintaining these parts ensures a smooth and quiet ride.