Editing Engine (section)

=== Sound levels ===
Vehicle noise is predominantly from the engine at low vehicle speeds and from tires and the air flowing past the vehicle at higher speeds.<ref>{{cite journal|first=C. Michael |last=Hogan |title=Analysis of Highway Noise |journal=Journal of Water, Air, and Soil Pollution |volume=2 |issue=3 |pages=387–92 |date=September 1973 |issn=0049-6979 |doi=10.1007/BF00159677 |bibcode=1973WASP....2..387H |s2cid=109914430 }}</ref> Electric motors are quieter than internal combustion engines. Thrust-producing engines, such as turbofans, turbojets and rockets emit the greatest amount of noise due to the way their thrust-producing, high-velocity exhaust streams interact with the surrounding stationary air.
Noise reduction technology includes intake and exhaust system [[muffler]]s (silencers) on gasoline and diesel engines and noise attenuation liners in turbofan inlets.