hat is Noise Mapping ? A Noise Map is a map of an area which is coloured according to the noise levels in the area. Sometimes, the noise levels may be shown by contour lines which show the boundaries between different noise levels in an area. The noise levels over an area will be varying all the time. For example, noise levels may rise as a vehicle approaches, and reduce again after it has passed. This would cause a short-term variations in noise level. In the slightly longer term, noise levels may be higher in peak periods when the roads are busy, and lower in off-peak periods. Then again, there is a greater volume of activity from more people and traffic in the day-time than in the evening or at night. In the longer term, wind, weather and season all affect noise levels. This means that it is not possible to say with confidence what the noise level will be at any particular point at any instant in time, but where the noise sources are well-defined, such as road or rail traffic, or aircraft, then it is possible to say with some confidence what the long-term average noise level will be. It may be thought that the best way of doing this is by measurement, but experience shows that this is not the case. For a start, a long-term average must be measured over a long period of time. Secondly, to obtain complete coverage of an area, measurements would have to be made on private property, where access might be difficult, and thirdly, measurements cannot distinguish the different sources of noise, so they would not be able to give information on how much noise was being made by each of the sources in an area. For these and other reasons, noise mapping is usually done by calculation based on a computerised noise model of an area, although measurements may be appropriate in some cases. A further benefit of having a noise model is that it can be used to assess the effects of transportation and other plans. Thus the effect of a proposed new road can be assessed and suitable noise mitigation can be designed to minimise its impact. This is particularly important in noise action planning, where a cost-benefit analysis of various options can be tested before a decision is made. iFluids Engineering Vivek Mariappan Environmental Engineer Consultant SoundPLAN CadnaA

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Noise Mapping (Sound Level Modelling)
Noise has a multitude of effects on our environment and society. As part of modern
civilizations standards and legal ruling have been developed and are continuously updated to
set parameters for equipment limits, city, state or federal requirements. These standards and
legal rulings regulate what is consider audible, acceptable, allowable or significant.
What is Noise ?
Noise is often defined as ‘sound which is undesired by the recipient’. A sound which one
person finds enjoyable, such as some music perhaps, could be very annoying to another
person who doesn’t want to hear it. Since it is quite probable that whatever the noise, there
will be someone who doesn’t like it, there is a common presumption that all sound is
bad. This presumption is even the basis of some legislation, which often seeks to limit sound
levels on the basis that any sound could be annoying to someone.
However, this presumption is by no means always true. Individual sensitivity to noise varies
greatly and some people are not bothered by noise that would be intolerable to
others. Moreover, there are many situations where noise is appropriate: for example a football
match conducted in silence would be unnatural and hardly enjoyable for fans.
In English law, it is illegal to create noise which amounts to a nuisance, but in Common Law,
the test is whether an ordinary person, taking account of the circumstances, would find the
noise to interfere with the ‘enjoyment’ of their land to a material degree. Statute Law has
changed the situation in recent years, and objective noise tests are becoming more important.

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It is relatively easy to devise measurement units that can measure sound level, but because
noise perception is subjective (ie it depends on the listener), acousticians have not been able
to find a perfect unit or index for measuring noise.
This means that acousticians use a variety of measurement units that describe sound levels in
a variety of ways. Using these as a guide to the impact of noise on people requires careful
interpretation by skilled practitioners.
However, increasing regulation, both national and European, is changing the situation, so that
assessments are now more likely to depend on taking noise measurements in accordance with
a defined procedure and for the result to be compared with objective guidelines.
What is noise mapping?
Sound modelling has become an increasingly popular tool in acoustics, often for assessing the
impact of potential developments or for predicting the effects of noise mitigation
methods. Using formulae for predicting the creation and propagation of sound that are
provided in various standards and guidance and combining this with illustrative tools and
visual aids it is possible to calculate and map out decibel levels, providing useful information
that can help acoustic professionals.
A Noise Map is a map of an area which is coloured according to the noise levels in the
area. Sometimes, the noise levels may be shown by contour lines which show the boundaries
between different noise levels in an area.
The noise levels over an area will be varying all the time. For example, noise levels may rise
as a vehicle approaches, and reduce again after it has passed. This would cause a short-term
variations in noise level. In the slightly longer term, noise levels may be higher in peak
periods when the roads are busy, and lower in off-peak periods. Then again, there is a greater
volume of activity from more people and traffic in the day-time than in the evening or at
night. In the longer term, wind, weather and season all affect noise levels.
This means that it is not possible to say with confidence what the noise level will be at any
particular point at any instant in time, but where the noise sources are well-defined, such as
road or rail traffic, or aircraft, then it is possible to say with some confidence what the long-
term average noise level will be.
It may be thought that the best way of doing this is by measurement, but experience shows
that this is not the case. For a start, a long-term average must be measured over a long period
of time. Secondly, to obtain complete coverage of an area, measurements would have to be
made on private property, where access might be difficult, and thirdly, measurements cannot
distinguish the different sources of noise, so they would not be able to give information on
how much noise was being made by each of the sources in an area.
For these and other reasons, noise mapping is usually done by calculation based on a
computerised noise model of an area, although measurements may be appropriate in some
cases.

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What is a noise model ?
A NoiseMap noise model supplies all the data that NoiseMap requires to undertake noise
predictions.
At its simplest level, it can be regarded as a special form of digital map. The NoiseMap
model must describe:
• Noise source, such as roads, vehicles, plant, railway tracks
• Transmission path, particularly noise barriers, ground topography and hard or soft
ground cover
• Receiver locations
However, the user does not need to know in detail how these affect the generation and spread
of noise. For example, a barrier may screen part of road from some receivers, but other
receivers may not have any screening. The user does not need to consider this detail. You
only have to make sure that you put into the model the various objects which affect the
spread of noise, and NoiseMap will work out how these affect the noise level at any point of
interest.
The noise model resembles the three-dimensional physical situation, but only includes the
features which affect the spread of noise. These only need to be shown to a level of detail and
accuracy which will give acceptable noise calculations.
A further benefit of having a noise model is that it can be used to assess the effects of
transportation and other plans. Thus the effect of a proposed new road can be assessed and
suitable noise mitigation can be designed to minimise its impact. This is particularly
important in noise action planning, where a cost-benefit analysis of various options can be
tested before a decision is made.
From modelling sound sources using real-world measured levels that are converted into
sound power levels, or using sound power levels provided by manufacturers that have been
taken in laboratory environments, it's possible to model the propagation of the noise
generated by these objects in various scenarios. By taking traffic information or spot
measurements and combining them with aerial views it is possible to map out the effects of
an existing road on a hypothetical development, or predict the screening required to bring
levels below the requirements given for minimising health effects.

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European Noise Directive
The Environmental Noise Directive requires noise levels to be assessed from road traffic,
railways, major airports and industry. It is not a requirement to assess noise generated by
other activities, such as may arise from gardening, construction work, sports and leisure
activities, pop concerts and the like.
Noise maps produced for the Environmental Noise Directive represent the annual average
noise levels at a height of 4 metres above the local ground level.
The Environmental Noise Directive requires noise levels to be assessed in terms of Lden and
Lnight.
Lden is the equivalent continuous noise level over a whole 24-hour period, but with noise in
the evening (19:00 to 23:00) increased by 5 dB(A) and noise at night (23:00 to 07:00)
increased by 10 dB(A) to reflect the greater noise-sensitivity of people at those times.
Lnight is the equivalent continuous noise level over the night-time period (23:00 to 07:00).
Lnight does not contain any night-time noise weighting.
The UK government has published a procedure that allows LA10 (18-hour) levels to be
converted into Lden and Lnight values. Because motorways carry a higher proportion of
traffic at night compared with other roads, the conversion factors for motorways are different
from the conversion factors for other roads.

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UK Legislation
UK Legislation regulates most types of noise emission – whether from transportation,
industrial, workplace, domestic or leisure sources. The legislation applies at many different
levels – for example there are legal controls on the amount of noise most types of machinery
can generate, including road vehicles and aircraft, construction plant and even some types of
gardening equipment, such as lawnmowers. Together, there is now a huge volume of noise
legislation and guidance. Some of this is given on our Links page.
There are also planning controls on the siting of noisy installations and also on the siting of
noise-sensitive buildings, such as houses and schools. This means that when a new factory is
planned, it must not cause undue noise at noise-sensitive premises, and also when new
housing is planned, it must not be exposed to excessive noise.
New or improved roads are also subject to detailed noise assessment to ensure that they are
planned and designed to take noise exposure into account. This work is complex and
nowadays noise mapping is essential to the process.
Heavy investment is taking place to improve the UK railway network, with the introduction
of faster trains providing a more frequent service. New rail links are also being planned or
constructed, including extensions to the Docklands Light Railway and the proposed
CrossRail link through Central London.
Again, noise mapping is being used to assess the potential not only for noise from the
operational railway, but also from construction sites. These can be particularly problematic,
as much railway construction work has to be done in ‘engineering hours’, ie when train
services stop for the night.
When applying for planning permission for new housing, planning authorities require an
assessment of the noise exposure, and again noise mapping is an ideal way of providing this
information.
Equally, the noise exposure arising from new factories can easily be illustrated by noise
maps.
Article Source: http://www.noisemap.ltd.uk/ , http://www.masenv.co.uk/, http://navcon.com/
Interested in our noise mapping services?
Our in-house Subject Matter Experts and design team uses below following softwares:
DataKustik's CadnaA environmental noise mapping software.
CadnaA offers a broad range of features for complex modelling scenarios and is widely used
in the acoustics industry, including consideration of ground height, road prediction using
CRTN and other object types such as foliage, railway and line/area sources.

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SoundPLAN offers high end simulation software for noise modeling and air pollution
calculations.
SoundPLAN Noise is following a standards based approach. With this software you can work
in accordance to the regulations that apply in your area. SoundPLAN has implemented over
50 regulations for road noise, train noise, noise inside buildings, general industrial noise and
aircraft noise.
SoundPLAN understands itself as an advanced planning tool, not as a purely academic
exercise, thus the program has a strong focus on what is needed to pinpoint the noise
problems and suggest a path to fix them.
iFluids Engineering Noise Mapping / Sound Modelling Services
• Noise Mapping Services
• Gas Compressor Station
• Traffic & Automotive Noise
• HVAC Noise Analysis
• Wind Energy Noise Study
• Building Acoustic Measurements
• Blast Noise Measurements
• Turbine Sound Power
• Road Traffic Noise
• Construction Noise
• Industrial Noise
• Railway Noise

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• Environmental Noise
• or any type of Noise?
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