Environmental Acoustics (Noise and Vibration)

Environmental acoustics is concerned with noise and vibration caused by railways, road traffic, aircraft, industrial equipment and recreational activities. The main aim of these studies is to reduce levels of environmental noise and vibration. Research work now also has a focus on the positive use of sound in urban environments for generating soundscapes and tranquillity. Environmental noise is an accumulation of noise pollution that occurs outside. This noise can be caused by transport, industrial, and recreational activities.

Noise is frequently described as ‘unwanted sound‘. Within this context, environmental noise is generally present in some form in all areas of human, animal, or environmental activity. The effects in humans of exposure to environmental noise may vary from emotional to physiological and psychological.

Noise at low levels is not necessarily harmful. Environmental noise can also convey a sense of liveliness in an area, which can be desirable. However, the adverse effects of noise exposure (i.e. noise pollution) could include: interference with speech or other ‘desired’ sounds, annoyance, sleep disturbance, anxiety, hearing damage and stress-related cardiovascular health problems.

As a result, environmental noise is studied, regulated, and monitored by many governments and institutions around the world. This creates a number of different occupations. The basis of all decisions is supported by the objective and accurate measurement of noise. Noise is measured in decibels (dB) using a pattern-approved sound level meter. The measurements are typically taken over a period of weeks, in all weather conditions.

Noise from transportation is typically emitted by machinery (e.g. the engine or exhaust) and aerodynamic noise (see aerodynamics and aircraft noise) caused by the compression and friction in the air around the vessel during motion. Environmental noise from the railway specifically is variable depending on the speed and quality of the tracks used for transportation.

Industrial and recreational noise could be generated by a multitude of different sources and processes. Industrial noise can be generated by factories and plants (i.e., product fabrication or assembly), power generation (hydroelectricity or wind turbines), construction activities, or agricultural and meat processing facilities. Sources of recreational noise vary widely but they can include music festivals, shooting ranges, sporting events, car racing, woodworking, pubs, people’s activities on the street, etc.

Sound propagation outdoors is subject to meteorological effects (e.g. wind, temperature) that affect the distance, speed, and direction with which environmental noise travels from a source to a listener.

Environmental noise, health effects and noise and quality of life show a direct correlation. The increase of environmental noise, especially for those living near railways and airports, has created, stress, anxiety, and even conflict. Getting adequate and quality sleep is difficult for those who live in areas of high noise exposure. When the body is at rest, noise stimuli is continually being presented in the environment. The body responds to these sounds which can negatively affect sleep (car horn during the night, fast train passing nearby)

High exposure to environmental noise can play a role in cardiovascular disease. Noise can raise blood pressure, change heart rates, and release stress hormones. Consistent changes in these health stats can lead to risks for hypertension, arteriosclerosis, and even more serious events such as a stroke or myocardial infarction.

The European directive 2002/49/EC gives a definition for environmental noise. The main goal is to create an integrated noise management system. The Environmental Noise Directive (END) was created in the European Union to provide guidelines, laws, and standards in the management of environmental noise. The END has created noise mapping, noise action plans, and quiet areas to control environmental noise and the negative effects it can have on individuals.

The implementation is divided into phases: In the first phase, the member states shall inform about major roads with more than six million vehicles a year, major railways with more than 60,000 trains per year, major airports with more than 50,000 movements per year and metropolitan areas with more than 250,000 inhabitants. In the second phase, these numbers are halved; only the criteria for airports remains unchanged. In the third and the following phases, the methods for calculation of the noise levels will change while the criteria remains unchanged. Each phase consists of three steps: the collection of the data from the main sources of noise, strategic noise maps and action plans. The countries listed below follow the guidelines of the European Union.