Industrial noise

Industrial noise pollution is an ever growing problem and its management is centred around many pieces of legislation, standards, guidance documents, etc. many of which frequently contradict each other. There are two main viewpoints, the more obvious of which is the quantification and control of a noise nuisance, usually in response to a complaint. Secondly, we have planning considerations where a potential nuisance or loss of amenity is anticipated and planning refusal or control conditions are imposed.
Noise-sensitive areas, i.e. the likely recipients of environmental noise, can be very varied: I have worked on environmental noise problems in offices, hover craft passenger decks, bird roosting sites, and shark aquariums. The vast majority of environmental noise problems, however, are associated with housing, particularly night time hours when peoples sleep may be disturbed. Sources of environmental noise are numerous but most can be covered by four main headings - Industrial Noise, Construction Noise, Leisure Noise, and Traffic Noise.
How Annoying is a Noise?
We can begin with the level of the noise - the louder it is the greater the risk of disturbance. The nature of the noise is also important e.g. a tonal sound (a hum, whine or whistle) will be more disturbing than a broad spread of frequencies (few would be disturbed by waves on the beach, even though it can be quite noisy). Intermittent noise can also attract attention beyond its true noise level, such as a thermostatically controlled chiller.
How disturbing a noise is will often be dependent on the amount of masking noise or background noise there is. One industrial noise standard, for instance, rates industrial noise by how much it exceeds background noise.
Numerous psychological effects should also be considered, not only in how we judge the noise, but in the choice of measurement and assessment methods. For a given noise level a lawn mower is likely to be less disturbing than a hi-fi played loudly with the windows open, simply because one will be regarded as reasonable while the other is less so. Other types of noise are inherently disturbing such as grinding, gun shots, dog barks, and the 90’s problem of the repetitive thump of modern dance music.
All this leaves us with very few clear, generic targets for the control of noise and much scope for arguments and debates, frequently in a courtroom. The good acoustic consultant, however, should be experienced enough and should have the appropriate range of analytical skills and tools to be guided by the various standards, etc. but also to disagree, modify, or interpret the standards if he or she feels that the situation is sufficiently unique to merit it.
Industrial Noise
BS 4142: 1990 "Rating Industrial Noise Affecting Mixed Residential and Industrial Areas" is the most important guidance document here and is the one most frequently used by environmental health officers to determine the degree of nuisance from a factory.
Basically, the alleged source of nuisance is measured (or predicted) and adjusted for disturbing features such as tones and intermittancy. This adjusted level is then compared with the background noise and a sliding scale from positively justified complaints to positively no justified complaints can then be applied.