Broadly speaking, environmental noise refers to noise from a development which affects the surrounding area. This could be noise from anything from a small extract fan to a large factory, and also encompasses traffic noise.
Noise surveys are the cornerstone of most acoustic consultancy. By measuring existing noise levels in an area, we are able to establish an appropriate noise level for new noise sources to avoid disturbance and ‘noise creep’. We are also able to calibrate noise maps (see below) to show how sound propagates across a built up area.
Noise surveys are also used to assess the impact of environmental noise on a new development, particularly residential developments, where they allow us to establish the acoustic strategy for ventilations and facades (BS 8233 assessment).
Where new noise sources will be introduced, noise surveys are the basis for a BS 4142 assessment (see below) to establish the level of disturbance occasioned to surrounding premises.
Noise Mapping and Modelling
For complex sites, noise modelling is a great way to investigate how new noise sources will affect the surrounding area. Models allow us to take into account factors such as the landscape, screening from buildings, and the location of new noise sources/
We can calibrate models using the data gathered from noise surveys, which means that where there are multiple noise sources in an area (e.g. roads, industry, rail) these can be accurately represented. Models also allow us to optimise mitigation measures such as bunding and noise barriers, saving money for the client whilst making sure the surrounding area is appropriately protected from noise.
BS 4142 Assessment
BS 4142 is the standard used to assess the potential for disturbance arising from industrial and commercial noise sources. In a BS 4142 assessment, the noise from an existing or future noise source is compared against the existing background sound level. Penalties are applied for acoustically distinctive characteristics such as intermittency or tonality. Based on the difference between the ‘rating level’ and background, and taking into account the acoustic context of the area, the likelihood of disturbance to surrounding areas can be predicted.
A BS 4142 assessment is typically required at planning stage for new industrial and commercial noise sources. It can also be carried out where noise complaints are received to investigate whether there is a basis for the complaints.
Noise Impact Assessment
Planning conditions for new developments will typically require that a noise impact assessment is carried out.
Noise impact assessment involves comparing the predicted noise levels from the proposed development against the prevailing background noise levels.
A noise survey is carried out to quantify the existing sound environment. The anticipated noise levels generated by the development can be predicted in a number of ways, including noise modelling, predictions based on manufacturers’ noise data, or predictions based on noise levels measured at other sites or venues.
Noise impact assessments are required for any scheme where noise might impact upon neighbouring sites. This can be anything from a new cafe or bar in a mixed use development, or ventilation plant associated with a new residential development, to a new industrial site.