For vehicle engines
modification of exhaust pipe for speed acceleration or using poor quality exhaust pipe may increase noise
Sources of noise
Bulk traffic of noise from the combination of all noise from vehicles travelling along a road
At low traffic speeds: vehicle engines transmission exhausts and brakes
At high speeds: interaction between tires and the road air disturbance by moving vehicles
Intermittent traffic noise is caused by individual vehicles
heavy vehicles
Modified cars and motorcycles
Noisy exhaust systems
Loud music from vehicles
Empty heavy vehicles
Driver behavior