Noise, Vibration and Acoustics Consultancy from the Institute of Sound and Vibration Research
Written by Bob Davis
Original version © 2002, ISVR University of Southampton. All rights reserved.
Noise is unwanted sound. Sound is a form of energy which is
transmitted through the air and is detected by the ear as rapid
changes in pressure. The air is set into motion by the source of
the sound, which is most often a vibrating surface or a turbulent
flow of air. The loudness and character of a steady sound are
determined by its frequency (measured in Hertz or Hz) and its level
(measured in decibels or dB). In this handbook, noise levels will
be stated in dB(A) - this is the noise
level measured by a meter which simulates the response of the human
ear to sounds of different frequencies. Noise levels in dB(A) are
almost universally used for the assessment of noise in the
community and in the workplace.
Depending on the level of noise and the duration of exposure,
noise can cause varying degrees of annoyance or difficulties in
communication. It can disturb relaxation or sleep, or can have
adverse health effects including damage to the hearing. This
handbook is about noise affecting people living near industry. In
this situation, the noise levels experienced are such that the
worst adverse effects of noise are annoyance and sleep disturbance.
Some noise may cause only minor and temporary irritation, but in
other cases noise can cause such a strong reaction that an
individual's ability to relax or concentrate is severely
Peoples' response to noise, particularly to noise from outside their own home, is highly variable. Some people are far more or less tolerant than others, for a variety of reasons, many of them psychological. There are obvious factors such as 'lifestyle' - a person who is at work during the day is obviously less likely to complain about daytime noise than is the shift-worker next door who has to sleep during the day. However, an important factor is the attitude of the individual towards the source of noise - people are far less tolerant of noise if they think that the noise-maker is inconsiderate or unreasonable.
Noise and vibration are inseparable - noise is generated by a
vibrating surface or body of air or gas. However, vibration itself
is a potential cause of problems. Some heavy engineering processes,
particularly the operation of forging hammers, can result in
significant energy being transmitted to the ground through machine
foundations. This can be transmitted to nearby houses and can
sometimes be felt as actual motion, because the human body is a
very sensitive vibration detector.
High levels of vibration can cause physical personal injury or
damage to buildings. However, vibration from industry affecting
nearby houses is never so intense that there is any conceivable
risk of any health effects, and building damage from any source of
ground-borne vibration is extremely rare. However, vibration can be
annoying and disturbing.
Apart from causing detectable (although in fact very slight) motion in nearby houses, ground-borne vibration from industry can also cause noise problems in these houses. This is because the internal surfaces of houses (walls, floors and ceilings) can be caused to vibrate by vibrations transmitted from the ground through the foundations and building structure. These surfaces can then radiate low-frequency noise ('thumps' and 'rumbles') rather in the manner of large loudspeakers. People living near factories containing equipment such as forging hammers, large presses or guillotines can sometimes hear the resulting 'thumps' inside their houses, although the vibration itself - the actual motion of the structure- is too slight to be felt. Ground-borne vibration can also be detected in other ways - objects such as slightly loose central heating radiators, and glasses or china in light contact, may squeak or rattle.
Residents who can feel vibration, or hear the 'thumps' and 'rattles' it sometimes causes, are often more concerned about the possibility of damage to their houses (which is most unlikely to be caused) than they are annoyed by the actual disturbance to themselves.
Problems arising from ground-borne vibration are relatively rare, although drop-hammers can cause detectable ground vibration up to around 100 metres away, and sometimes at greater distances in some ground conditions. This handbook concentrates on the far more widespread situation where houses near forges and foundries are affected by airborne noise. However, the possibility of a 'noise' problem being a vibration' problem should be borne in mind - noises caused by ground-borne vibration must be distinguished from the effects of noise which is transmitted through the air (airborne noise) since different control methods are required and incorrect diagnosis can lead to costly wasted work. Further information about noise and vibration will be found in Annex 2.
This section explains briefly the Standards and Regulations
which apply to noise from industry in England. There may be minor
differences and exceptions in Wales. Scotland and Northern Ireland.
Different standards and Regulations will apply elsewhere.
Where planning consent is required for a new site, new buildings
or a change of use, this consent often includes conditions to limit
noise emission. These conditions might include restrictions on
hours of use or methods of working, or they may specify maximum
noise levels which are not to be exceeded at specified times of the
day or night. These Conditions are enforced by the Local Authority.
A breach of a planning condition can lead to an Enforcement Notice
and prosecution. If noise affecting other premises amounts to a
nuisance, a Local Authority can also use its powers under the
Environmental Protection Act (the 'EPA' - see below) to abate the
Many industrial sites do not have a formal planning consent,
because a current use which has been carried on for more than ten
years can be considered lawful. Many forges and foundries fall into
this category. In these cases, if noise causes a nuisance to
neighbours a Local Authority would use its powers under Section 80
of the EPA. If the Local Authority is satisfied that noise amounts
to a nuisance, it has to serve an Abatement Notice. The company can
appeal against a Notice within a specified period. Non-compliance
with a Notice can lead to prosecution. If a company can show that
it has applied the best practicable means of reducing noise (often
termed 'Best Available Techniques' or 'BAT') this can provide a
ground for an Appeal against the Notice or for defence against
Where noise is causing a nuisance, private individuals can take action against an industrial site under Section 82 of the EPA, or under common law, even when the Local Authority choose not to do so. Such actions are rare, however.
Noise is a nuisance when it materially affects people's amenity. There are no fixed limits for industrial noise affecting houses - what is or is not considered acceptable or a nuisance depends on local circumstances. However, the following table illustrates the general range of unacceptable and acceptable noise levels from industry in a 'typical' built-up environment of mixed residential and industrial areas.
|Day (7 am - 7 pm)||50 - 55||55 - 60||60+|
|Evening (7 pm - 11 pm)||45 - 50||50 - 55||55+|
|Night (11 pm - 7 am)||40 - 45||45 - 50||50+|
These are 'broad brush' values and must not be taken as specific guidance for any particular site or situation. Higher noise levels might be acceptable in areas exposed to high levels of road traffic noise from trunk roads or motorways. Lower noise levels might be needed in quieter areas. An important factor is the character of the industrial noise. Noise which contains bangs and crashes is far more annoying and disturbing than steady noise of the same average level. The regular 'banging' caused by forging hammers is a particularly distinctive and potentially disturbing noise. For these types of noise, the noise levels in the Table should be reduced by at least 5 dB(A).
There is a British Standard (BS 4142 - reference 1) which sets
out a method of predicting whether noise from an industrial site is
likely to provoke complaints. This standard is based on comparing
the noise (measured or predicted) from the premises, as received at
any house, with the background noise level at the same position
when the industrial operation is stopped. The method includes a
means of allowing for the 'character' of the noise, by penalising
noise which contains bangs, crashes, whines or hums.
Evidence based on the use of BS 4142 is generally accepted in the Courts to demonstrate (or to dispute) the existence of a noise nuisance. Noise limits in Planning Conditions are usually based on consideration of BS 4142. The Standard is widely used (and often misused) and will inevitably be quoted whenever an industrial noise problem arises. However, proper application of the Standard requires expertise and judgement and a good understanding of its limitations.
Some companies operate voluntary environmental policies and
procedures which include the assessment of noise emitted to their
locality. These procedures might include, for example, regular
noise monitoring at key locations and a method of assessing the
extent of any change in noise emission likely to result from
changes in plant or operating methods. Some companies formally
accredit these policies under ISO 14001 (ref 2). In some sectors of
industry, ISO 14001 accreditation is a customer requirement.
The introduction of Integrated Pollution Prevention and Control (IPPC) is likely to have a significant impact on the way noise from foundries and forges is controlled. IPPC will broaden the scope of existing pollution controls , which currently apply to certain industrial processes (including ferrous foundries and but excluding forges) to include noise and vibration. One objective of IPPC will be to encourage good practice (BAT).
This handbook is not concerned directly with noise in the
workplace, although reducing noise 'at source' by quietening a
process or operation can often result in benefits both in the
workplace and in the neighbouring area.
Noise levels in the workplace are covered in the UK by the Noise at Work Regulations 1989 (ref 3). An HSE document (ref.4) explains the Regulations and gives further guidance. New regulations on noise at work will appear in a revised EU Physical Agents Directive, currently being discussed. These changes will work through into UK regulations.
Regulations and enforcement procedures relating to environmental matters. including management of noise, are constantly changing. As far as possible. keep up to date by extracting information from trade journals and government circulars Trade Associations are a major source of such information.
Original version © 2002, ISVR University of Southampton. All rights reserved.