Noise Modelling and Mapping

Why Use Noise Modelling

Measurements describe the noise that exists today. Modelling predicts the noise that will exist once a development is built, a road is opened or new plant is installed. It also allows different options to be compared, such as barrier heights, building layouts or plant locations, before any money is spent on construction.

Our project work includes detailed predictive modelling for hotel developments, operational road noise modelling, room acoustic modelling for performance and event venues, and 3D noise modelling for industrial sites and plant. The results support planning applications, environmental impact assessments and detailed design.

How a Noise Model Is Built

We use 3D noise modelling software to create a digital model of the site and its surroundings. The accuracy of the predictions depends on the quality of the inputs, so each model is built from the best data available.

Ground levels, buildings and existing barriers from survey data, mapping or drawings
Noise sources such as roads, railways, plant, vehicles and industrial activities, with their sound power levels or traffic data
Ground type, which affects how sound is absorbed between source and receiver
Receiver points at homes, schools and other sensitive locations, at the relevant floor heights

Each source and receiver is checked before calculations are run, because a single error in a building height or source level can change the results noticeably. Where possible, models are checked against baseline noise survey measurements so the predictions reflect real conditions.

Prediction Methods and Standards

The calculation method depends on the type of source and the purpose of the assessment. Commonly used methods include:

ISO 9613-2, a general method for calculating the attenuation of sound outdoors, widely used for industrial and plant noise
CRTN (Calculation of Road Traffic Noise), the long established method for road traffic noise in the UK and Ireland
CNOSSOS-EU, the common European methods used for strategic noise mapping under the Environmental Noise Directive

We select the method that suits the project and the requirements of the planning authority or road authority, and we state the method and assumptions clearly in our reports.

Road Traffic Noise Modelling

New roads, road upgrades and residential developments near busy roads all need traffic noise assessed. Using traffic flows, speeds and the proportion of heavy vehicles, we predict noise levels at existing and proposed receptors for the opening year and future design years.

The results show where mitigation is needed, such as noise barriers, low noise road surfaces or changes to building layout and orientation. For residential schemes, predicted facade levels feed directly into facade sound insulation assessments, which set the glazing and ventilation performance needed to achieve suitable internal levels under BS 8233:2014.

Industrial and Plant Noise Modelling

Industrial sites, energy projects and data centres often have many sources operating together, spread across a large site. Modelling lets us predict the combined noise at nearby homes and test how it changes with different plant selections, layouts, operating modes or mitigation.

Results are typically assessed against planning or licence limits, or using BS 4142:2014+A1:2019 for commercial and industrial sound affecting residential receptors. The model can then be used to set noise limits for individual items of plant, giving designers and suppliers clear targets. See also our industrial noise control and plant noise assessments.

Noise Maps and Contours

A noise map shows predicted levels across an area as coloured contours, either at a set height above ground or on building facades. Maps make it easy to see which parts of a site are most exposed, where mitigation is most effective, and how a proposal changes noise in the surrounding area. On residential schemes, facade maps also show which apartments face the highest levels, helping architects plan room layouts so that bedrooms are placed on quieter elevations where possible.

We produce maps for daytime and night time periods and, where required, for indicators such as Lden and Lnight. Before and after maps are a clear way of presenting the effect of a proposal to planning authorities, design teams and the public.

Using Models in Planning and EIA

Noise modelling is often central to the noise and vibration chapter of an environmental impact assessment report, and to noise assessments submitted with planning applications. Predictions are made for the construction phase, the operational phase and, where relevant, future traffic growth, so that the change in noise at each receptor can be assessed.

The model also helps when planning authorities request further information. Alternative layouts or mitigation can be tested quickly and the results reported in the same format as the original assessment. Where a permission includes noise limits, the model can be used to show how they will be met and to identify where compliance surveys should be carried out once the development is operating.

Room Acoustic Modelling

Room acoustic modelling predicts how sound behaves inside a space. It is used for theatres, concert and event venues, conference rooms, atriums and large public spaces where speech clarity or music quality matters.

The model predicts parameters such as reverberation time, clarity and speech intelligibility, using the room geometry and the absorption of each surface. Parameters are defined in line with ISO 3382, so predictions can later be checked by on site reverberation time testing. Modelling helps decide the amount and position of acoustic treatment before finishes are fixed.

Frequently Asked Questions

How accurate are noise model predictions?

Accuracy depends on the quality of the input data and the method used. ISO 9613-2, for example, states an estimated accuracy for its calculations under defined conditions. Using reliable source data, accurate terrain and calibration against measured baseline levels gives the most dependable results. We state the key assumptions in every report.

Do I need a noise survey as well as a model?

Usually yes. A baseline survey records existing noise levels, which are needed for most assessments, including BS 4142 and environmental impact assessments. Survey results can also be used to check that the model reproduces existing conditions before it is used to predict future scenarios.

What information do you need to build a model?

Typically we need site layout drawings, building heights, topographical data, details of the noise sources and the receptors of interest. For roads, we need traffic flows, speeds and heavy vehicle percentages. For plant, manufacturer sound power data is best. Where data is not yet available, typical values can be used and refined later.

What are Lden and Lnight?

Lden is a day evening night level, a 24 hour average with penalties of 5 dB added to evening noise and 10 dB to night time noise. Lnight is the average level over the night period. Both are used in strategic noise mapping under the Environmental Noise Directive and in some planning assessments.

Can modelling be used to design noise barriers?

Yes. The model can test barrier heights, lengths and positions to find the most effective option. Barriers work best when they are close to either the source or the receiver and block the line of sight between them. Modelling shows the benefit at each receptor, helping balance acoustic performance against cost and visual impact.

Is room acoustic modelling only for large venues?

No. It is most common for theatres, concert halls and event spaces, but it is also useful for classrooms, lecture theatres, open plan offices, atriums and places of worship. Any space where speech clarity, music quality or noise build up matters can benefit from modelling before acoustic treatment is chosen.