Control the sound roots, such as noise caused by vehicles. People who use the vehicle to check the condition of the engine itself, well, first. Do not modify the exhaust noise caused others.
Controlling noise sources, such as voice control of vehicle. People who use the vehicle to check the condition of the engine itself well before. Not modified exhaust noise disturbing others.
Control of noise source, such as the control of noise from vehicles. People who use cars to check the engine of their own good. Not modified exhaust the noise of others.