In our surroundings, there are different sources emitting various types of environmental noise. Type of Environmental Noise Source Examples Transportation aircrafts, trains, road vehicles, vessels Industrial buildings factories - machineries, air-conditioning systems Commercial buildings office buildings - air-conditioning systems restaurants - air-conditioning systems, kitchen ventilating systems Construction sites site formation (e.g. excavation), piling, road work, demolition, renovation Domestic buildings mahjong playing, hi-fi, musical instruments Public places open markets, streets, parks Products intruder alarms of buildings and motor vehicles